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Purpose: For men with intermediate-risk prostate cancer treated with definitive therapy, the addition of androgen deprivation therapy (ADT) reduces the risk of distant metastasis and cancer-related mortality. However, the absolute benefit of ADT varies by baseline cancer risk. Estimates of prognosis have improved over time, and little is known about ADT decision making in the modern era. We sought to characterize variability and identify factors associated with intended ADT use within the Michigan Radiation Oncology Quality Consoritum (MROQC)., Materials and Methods: Patients with localized prostate cancer undergoing definitive radiation therapy were enrolled from June 9, 2020, to June 26, 2023 (n = 815). Prospective data were collected using standardized patient, physician, and physicist forms. Intended ADT use was prospectively defined and was the primary outcome. Associations with patient, tumor, and practice-related factors were tested with multivariable analyses. Random intercept modeling was used to estimate facility-level variability., Results: Five hundred seventy patients across 26 facilities were enrolled with intermediate-risk disease. ADT was intended for 46% of men (n = 262/570), which differed by National Comprehensive Cancer Network favorable intermediate-risk (23.5%, n = 38/172) versus unfavorable intermediate-risk disease (56.3%, n = 224/398; P < .001). After adjusting for the statewide case mix, the predicted probability of intended ADT use varied significantly across facilities, ranging from 15.4% (95% CI, 5.4%-37.0%) to 71.7% (95% CI, 57.0%-82.9%), with P < .01. Multivariable analyses showed that grade group 3 (OR, 4.60 [3.20-6.67]), ≥50% positive cores (OR, 2.15 [1.43-3.25]), and prostate-specific antigen 10 to 20 (OR, 1.87 [1.24-2.84]) were associated with ADT use. Area under the curve was improved when incorporating MRI adverse features (0.76) or radiation treatment variables (0.76), but there remained significant facility-level heterogeneity in all models evaluated (P < .05)., Conclusions: Within a state-wide consortium, there is substantial facility-level heterogeneity in intended ADT use for men with intermediate-risk prostate cancer. Future efforts are necessary to identify patients who will benefit most from ADT and to develop strategies to standardize appropriate use., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: To study the late urinary toxicity in patients with prostate cancer with prior transurethral resection of prostate (TURP) and treated with hypofractionated prostate radiation therapy., Methods and Materials: Patients diagnosed with prostate cancer, with a prior TURP, and treated with moderate or extreme hypofractionated intensity-modulated radiation therapy (moderate hypofractionated radiation therapy [MHRT], stereotactic body radiation therapy [SBRT]), were included in this study. Severity and duration of urinary symptoms observed during serial follow-up after at least 3 months from radiation therapy were graded per National Cancer Institute Common Terminology Criteria for Adverse Events v5.0 using information from a prospectively maintained institutional database. Impact of hypofractionation and other potential contributory factors on cumulative grade 2+ late urinary toxicity was analyzed with univariable and multivariable binary logistic regression., Results: A total of 203 eligible patients were included (MHRT = 114, 64-68 Gy/25#; SBRT = 89, 35-37.5 Gy/5#). Median time from TURP to radiation therapy was 10 months (IQR, 7-16 months), similar for MHRT and SBRT. Overall, mean cavity volume was 1.17 cc (IQR, 0.5-1.35 cc), whereas in MHRT and SBRT groups it was 1.03 cc (IQR, 0.4-1.15 cc) and 1.27 cc (IQR, 0.5-1.4 cc), respectively. At a median follow-up of 37 months, cumulative grade 3 and grade 2 late urinary toxicity was 8.4% (n = 17) and 23.2% (n = 47), respectively. Grade 3 symptoms were observed at median 29 months (IQR, 19-62 months) after radiation therapy completion, lasting for a median duration of 8 months (IQR, 2-14 months). Hematuria (6.4%) and urinary obstruction (3.4%) were the chief grade 3 symptoms. Multivariable analysis for age, diabetes, pelvic radiation therapy, fraction size, prostate volume, TURP to radiation therapy duration, and TURP cavity volume showed no significant association with late grade 2+ urinary toxicity., Conclusions: In this large cohort of patients with prior TURP and treated with hypofractionated prostate radiation therapy, incidence of severe late urinary adverse effects was <10%, mainly hematuria or urinary obstruction. Most of these were temporary, and no significant contributory factors were identified for late urinary morbidity after TURP and radiation therapy., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: The objective of this study was to characterize the conditional risk of developing grade 2+ urinary or gastrointestinal (GI) toxicity for patients treated with external beam radiation therapy in Radiation Therapy Oncology Group 0126. A secondary objective was to analyze baseline patient and treatment characteristics and determine their relevance in predicting toxicity both at the time of trial enrollment and at later points of follow-up., Methods and Materials: One thousand five hundred thirty-two patients with localized prostate cancer were enrolled between March 2002 and August 2008, of whom 1499 were eligible and included in data analysis with a median follow-up of 8.4 years (range, 0.02-13 years). Patients were treated with either 3-dimensional conformal radiation therapy or intensity-modulated radiation therapy according to institutional practice without the addition of androgen deprivation and randomized to receive either standard-dose radiation therapy of 70.2 Gy or dose-escalated radiation therapy of 79.2 Gy of radiation therapy to the prostate only with standard fractionation. Univariate and multivariate analyses were performed to determine whether initial factors were predictive of late toxicity at the time of treatment and at later time points., Results: As patients proceed further from completion of radiation therapy without the development of toxicity, the subsequent risk of both grade 2+ genitourinary (GU) and GI toxicity decreases with time. At the time of enrollment, the risk of developing grade 2+ toxicity over the next 5 years was 9.57% and 17.89%, respectively. After 5 years of toxicity-free survival, the risk of developing grade 2+ GU or GI toxicity in the subsequent 5 years was 3.02% and 1.54%, respectively. Baseline treatment and patient-related factors predicted late toxicity both at trial enrollment and after 2 years of toxicity-free survivorship. Baseline urinary dysfunction and dose-escalated radiation therapy were associated with increased late GU toxicity. Acute GI toxicity and dose-escalated radiation therapy were associated with increased risk of late GI toxicity. Treatment with intensity-modulated radiation therapy was associated with reduced risk of either toxicity., Conclusions: The conditional risk of grade 2+ toxicities decreases as patients proceed further from treatment, with most toxicities occurring in the first few years after treatment completion. Baseline patient and treatment characteristics remain relevant at both enrollment and later time points., (Copyright © 2024. Published by Elsevier Inc.)

Purpose: The focal radiation therapy (RT) boost technique was shown in a phase III randomized controlled trial (RCT) to improve prostate cancer outcomes without increasing toxicity. This technique relies on the accurate delineation of prostate tumors on MRI. A recent prospective study evaluated radiation oncologists' accuracy when asked to delineate prostate tumors on MRI and demonstrated high variability in tumor contours. We sought to evaluate the impact of contour variability and inaccuracy on predicted clinical outcomes. We hypothesized that radiation oncologists' contour inaccuracies would yield meaningfully worse clinical outcomes., Methods and Materials: Forty-five radiation oncologists and 2 expert radiologists contoured prostate tumors on 30 patient cases. Of these cases, those with CT simulation or diagnostic CT available were selected for analysis. A knowledge-based planning model was developed to generate focal RT boost plans for each contour per the RCT protocol. The probability of biochemical failure (BF) was determined using a model from the RCT. The primary metric evaluated was delta BF (DBF = Participant BF - Expert BF). An absolute increase in BF ≥5% was considered clinically meaningful., Results: Eight patient cases and 394 target volumes for focal RT boost planning were included in this analysis. In general, participant plans were associated with worse predicted clinical outcomes compared to the expert plan, with an average absolute increase in BF of 4.3%. Of participant plans, 37% were noted to have an absolute increase in BF of 5% or more., Conclusions: Radiation oncologists' attempts to contour tumor targets for focal RT boost are frequently inaccurate enough to yield meaningfully inferior clinical outcomes for patients., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Stereotactic body radiotherapy (SBRT) and immune checkpoint inhibitors (ICIs) could obtain a certain synergistic effect on bone and soft tissue sarcoma (BSTS). Given its low radiosensitivity, BSTS usually require an irradiation dose >65 Gy to achieve local control. Herein, we developed a non-classical SBRT technique called "onion-shaped simultaneous boost (OSB)," and reported a patient with prostatic leiomyosarcoma which received non-classical SBRT and other systemic treatments., Methods: In the case, a 49-year-old male patient was diagnosed with prostatic leiomyosarcoma in November 2018. In the radiotherapy plans, the maximum doses of the targets were more than 65 Gy, while the doses of the organs at risk (OARs) were strictly limited., Results: After receiving radiotherapy, ICI, and other multidisciplinary modalities, the patient achieved partial response (PR)., Conclusion: In this clinical case, we have observed that the OSB technique, which employs an increased per-fraction radiotherapy dose without the need to match the single-fraction doses typical of conventional SBRT, effectively enhances the therapeutic impact on leiomyosarcoma without an increase in radiotherapy-related side effects. By integrating the OSB technique with a multidisciplinary array of antineoplastic strategies, we can more effectively manage sarcomas in clinical practice., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background: This study assessed the biochemical disease-free survival (bDFS), prostate cancer-specific survival (PCSS), overall survival (OS), and side effects in patients aged < 70 and ≥ 70 years following definitive radiotherapy (RT). It also analysed the correlation between age at diagnosis and clinicopathological characteristics of prostate cancer (PCa)., Methods: The prognostic factors for bDFS, PCSS, and OS were determined through univariable and multivariable analyses. Two age groups were also compared in terms of acute and late grade ≥ 2 genitourinary (GU) and gastrointestinal (GI) toxicities, the predictors of which were determined through logistic regression analysis., Results: Of the 1,328 patients, 715 (53.8%) and 613 (46.2%) were aged < 70 and ≥ 70 years, respectively. Median follow-up time was 84.5 months. No significant differences in the 7-year bDFS (86.3% vs. 86.8%) and PCSS rates (92.9% vs. 93.3%) were found between the ≥ 70 and < 70 age groups. The multivariable analysis showed that advanced clinical T stage, high International Society of Urological Pathology (ISUP) grade, and high-risk disease independently predicted poor bDFS and PCSS. Metastatic lymph nodes were another bDFS prognostic factor. The multivariable analysis identified age ≥ 70 years, cardiac events at diagnosis, advanced stage, higher ISUP grade, and non-use of simultaneous integrated boost technique as negative factors for OS. Additionally, diabetes and transurethral resection of the prostate (TUR-P) independently predict late-grade ≥ 2 GU toxicity., Interpretation: Definitive RT is a safe and effective treatment for patients with localised PCa no matter their age. Although patients over 70 years have higher risk factors and comorbidities, their bDFS, PCSS, and toxicities were comparable to those of patients aged < 70 years.

Objective . To estimate dose rates delivered by using radioactive 198 Au nanoparticles for prostate cancer nanobrachytherapy, identifying contribution by photons and electrons emmited from the source. Approach . Utilizing in silico models, two different anatomical representations were compared: a mathematical model and a unstructured mesh model based on the International Commission on Radiological Protection (ICRP) Publication 145 phantom. Dose rates by activity were calculated to the tumor and nearby healthy tissues, including healthy prostate tissue, urinary bladder wall and rectum, using Monte Carlo code MCNP6.2. Main results . Results indicate that both models provide dose rate estimates within the same order of magnitude, with the mathematical model overestimating doses to the prostate and bladder by approximately 20% compared to the unstructured mesh model. The discrepancies for the tumor and rectum were below 4%. Photons emmited from the source were defined as the primary contributors to dose to other organs, while 97.9% of the dose to the tumor was due to electrons emmited from the source. Significance . Our findings emphasize the importance of model selection in dosimetry, particularly the advantages of using realistic anatomical phantoms for accurate dose calculations. The study demonstrates the feasibility and effectiveness of 198 Au nanoparticles in achieving high dose concentrations in tumor regions while minimizing exposure to surrounding healthy tissues. Beta emissions were found to be predominantly responsible for tumor dose delivery, reinforcing the potential of 198 Au nanoparticles in localized radiation therapy. We advocate for using realistic body phantoms in further research to enhance reliability in dosimetry for nanobrachytherapy, as the field still lacks dedicated protocols., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Background: Radiotherapy of the prostate and the pelvic lymph nodes (LN) is a part of the standard of care treatment for high-risk prostate cancer. The independent translational and rotational (i.e., six-degrees-of-freedom, [6DoF]) motion of the prostate and LN target during and between fractions can perturb the dose distribution. However, no standard dose reconstruction method accounting for differential 6DoF target motion is available., Purpose: We present a framework for monitoring motion-induced dose perturbations for two independently moving target volumes in 6DoF. The framework was used to determine the dose perturbation for the prostate and the LN target caused by differential 6DoF motion for a cohort of high-risk prostate cancer patients. As a potential first step toward real-time dose-guided high-risk prostate radiotherapy, we furthermore investigated if the dose reconstruction was fast enough for real-time application for both targets., Methods: Twenty high-risk prostate cancer patients were treated with 3-arc volumetric modulated arc therapy (VMAT). Kilovoltage intrafraction monitoring (KIM) with triggered kilovoltage (kV) images acquired every 3 throughout 7-10 fractions per patient was used for retrospective 6DoF intrafraction prostate motion estimation. The 6DoF interfraction LN motion was determined from a pelvic bone match between the planning CT and a post-treatment cone beam CT (CBCT). Using the retrospectively extracted motion, real-time 6DoF motion-including dose reconstruction was simulated using the in-house developed software DoseTracker. A data stream with the 6DoF target positions and linac parameters was broadcasted at a 3-Hz frequency to DoseTracker. In a continuous loop, DoseTracker calculated the target dose increments including the specified motion and, for comparison, without motion. The motion-induced change in D 99.5% for the prostate CTV (ΔD 99.5% ) and in D 98% for the LN CTV (ΔD 98% ) was calculated using the final cumulative dose of each fraction and averaged over all imaged fractions. The real-time reconstructed dose distribution of DoseTracker was benchmarked against a clinical treatment planning system (TPS) and it was investigated whether the calculation speed was fast enough to keep up with the incoming data stream., Results: Translational motion was largest in cranio-caudal (CC) direction (prostate: [-5.9, +8.4] mm; LN: [-9.9; +11.0] mm) and anterior-posterior (AP) direction (prostate:[-5.6; +6.9] mm; LN: [-9.6; +11.0] mm). The pitch was the largest rotation (prostate: [-22.5; +25.2] deg; LN: [-3.9; +5.5] deg). The prostate CTV ΔD 99.5% was [-16.2; +2.5]% for single fractions and [-3.0; +1.7]% when averaged over all imaged fractions. The LN CTV ΔD 98% was [-19.8; +1.2]% for single fractions and [-3.1; +0.9]% after averaging. Mean (Standard deviation) absolute dose errors in DoseTracker of 107.8% (Std: 1.9%) for the prostate and 105.5% (Std:1.4%) for the LN were corrected during dose reconstruction by automatically calculated normalization factors. It resulted in accurate calculation of the motion-induced dose errors with relative differences between DoseTracker and TPS dose calculations of -0.1% (Std: 0.5%) (prostate CTV ΔD 99.5% ) and -0.2% (Std: 0.5%) (LN CTV ΔD 98% ). The DoseTracker calculation was fast enough to keep up with the incoming inputs for all but two out of 107 184 dose calculations., Conclusion: Using the developed framework for dose perturbation monitoring, we found that the differential 6DoF target motion caused substantial dose perturbation for individual fractions, which largely averaged out after several fractions. The framework was shown to provide reliable dose calculations and a sufficiently high-dose reconstruction speed to be applicable in real-time., (© 2024 The Author(s). Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Purpose and Objective: Salvage radiotherapy (sRT) can have similar outcomes to adjuvant radiotherapy (aRT) if administered at the earliest evidence of biochemical recurrence. RADICALS-RT was the first trial to support this hypothesis and a policy of observation after radical prostatectomy (RP) with early sRT has become the new standard of care since then. This study assessed the impact of RADICALS-RT in the clinical practice regarding the timing of sRT for prostate cancer initially treated with RP., Methods: Data from 297 patients who underwent sRT after radical RP were retrospectively collected. Two groups were created and analyzed on the basis of the date of RADICALS-RT presentation at ESMO. After these results were released in October 2021, our institutional postoperative radiotherapy policy was revisited, and a third group was created and analyzed separately., Results: Median PSA for Groups 1, 2, and 3 were 0.33, 0.27, and 0.2, respectively. Less than one-third of patients in Groups 1 and 2 had a postoperative PSA of 0.2 ng/mL or less at the time of sRT. Group 3 showed statistically significant differences in median PSA at the time of sRT compared with Groups 1 and 2., Conclusions: RADICALS-RT demonstrated a significant impact on clinical practice only after being complemented with real local evidence., (© 2024 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.)

Background/aim: Radiotherapy is one of the most frequently used options for prostate cancer (PCa). However, adverse effects related to irradiation of surrounding normal organs are significant clinical concerns. Specifically, genitourinary toxicity can dramatically reduce the quality of life. This clinical trial investigated the efficacy of oral 5-aminolevulinic acid phosphate combined with sodium ferrous citrate (ALA-SFC) in patients treated with low-dose-rate brachytherapy (LDR-BT) using an iodine-125 seed source., Patients and Methods: The AMBER study was a prospective single-center trial involving patients with localized PCa who underwent LDR-BT without external-beam radiotherapy (jRCTs051190077). Fifty patients were included and instructed to take capsules of ALA-SFC twice a day (200 mg phosphate salt and 229.42 mg per day) for six months from the day of seed implantation (prescribed radiation dose of 160 Gy). Patient data were collected before implantation, during ALA-SFC treatment, and at 1, 3, 6, 9, and 12 months post-LDR-BT. The primary endpoint of this trial was urinary frequency at three months. Other patient-reported outcomes, investigator-reported adverse events, and oncological outcomes were secondary endpoints., Results: Of 50 enrolled cases (45 in the per-protocol analysis, 49 in the safety analysis), urinary frequency and its increase from baseline did not differ from 141 historical controls at any time point, including at three months post-LDR-BT. Propensity score matched analysis confirmed no time-course differences in frequency, volume, or urinary symptom scores between groups. Biochemical failure-free and metastasis-free survival also remained similar., Conclusion: Oral supplementation of ALA-SFC to LDR-BT did not alleviate radiation-induced toxicity or improve oncological outcomes., (Copyright © 2024, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

In this narrative review, we will explore the different options for salvage re-irradiation for locally recurrent prostate cancer. Brachytherapy (BT) and stereotactic body radiation therapy (SBRT) appear to be successful options. We detailed doses, volumes, oncological outcomes, and toxicity events to identify the best salvage strategy. Salvage reirradiation can only be proposed in certain cases, depending on the patient and the clinical scenario. Specific imaging and tests are needed to safely deliver this treatment., (Copyright © 2024. Published by Elsevier Masson SAS.)

Background: Posttreatment surveillance affects millions of cancer survivors, but empiric data to guide clinical practice are lacking. This study assessed whether the intensity of surveillance testing after radical prostatectomy or radiation therapy for localized prostate cancer is associated with overall survival., Methods: Men diagnosed with localized prostate cancer between 2005 and 2010 who underwent radical prostatectomy or radiation therapy at a Commission on Cancer-accredited facility were randomly sampled. Primary data collected from 10 147 patients sampled across 1007 facilities were linked with existing data from the National Cancer Database. Analysis examined whether intensity of surveillance measured as the number of prostate-specific antigen (PSA) tests in the first year after primary treatment (categorized as 0-1 [low intensity], 2 [medium], or ≥3 [high intensity] PSA tests) was associated with overall survival. Secondary outcomes included recurrence-free survival (RFS) and subsequent use of imaging tests, biopsy procedures, and salvage treatment., Results: Median follow-up exceeded 8 years from prostate cancer diagnosis. Overall survival was not statistically significantly different across surveillance intensity groups among radiation therapy (P = .59) or radical prostatectomy (P = .29) patients. RFS was not statistically significantly different across surveillance intensity groups for radiation therapy (P = .13) patients but was for radical prostatectomy (P = .01) patients with high intensity associated with the worst RFS. In both treatments, higher surveillance intensity was associated with more procedures and salvage treatments., Conclusions: In patients with localized prostate cancer, more frequent PSA surveillance testing after radical prostatectomy or radiation therapy was associated with increased procedures and salvage treatments but not overall survival., (© The Author(s) 2024. Published by Oxford University Press.)

Herein, we provide a non-exhaustive selection of the main clinical trials presented in 2023-2024 related to radiation-oncology used in the treatment of urological cancers including prostate cancer (radiotherapy of localized prostate cancer, post-prostatectomy irradiation, reirradiation, biochemical recurrence following local treatment, radiotherapy for metastatic cancer), muscle invasive bladder cancer and primary kidney cancer., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Radionuclide therapy, in particular peptide receptor radionuclide therapy (PRRT), has emerged as a valuable means to combat malignant tumors. The specific affinity of ACUPA peptide toward prostate-specific membrane antigen (PSMA) renders the successful development of PRRT for prostate cancer. The clinical outcome of PRRT is, however, generally challenged by moderate tumor uptake and off-target toxicity. Here, we report on a novel design of Sigma-1 receptor and PSMA dual-receptor targeted peptide (S1R/PSMA-P) for superior radionuclide imaging and therapy of prostate cancer. S1R/PSMA-P was acquired with good purity and could efficiently be labeled with 177 Lu to yield 177 Lu-S1R/PSMA-P with high specific activity and radiostability. Interestingly, 177 Lu-S1R/PSMA-P revealed greatly enhanced affinity to LNCaP cells over single-targeted control 177 Lu-PSMA-617. The single photon emission computed tomography (SPECT) imaging demonstrated exceptional uptake and retention of 177 Lu-S1R/PSMA-P in LNCaP tumor, affording about 2-fold better tumor accumulation while largely reduced uptake by most normal tissues compared to 177 Lu-PSMA-617. The selective uptake in LNCaP tumor was also visualized by positron emission tomography (PET) with 68 Ga-S1R/PSMA-P. In accordance, a single and low dosage of 177 Lu-S1R/PSMA-P at 11.1 MBq effectively suppressed tumor growth without causing apparent side effects. This dual-targeting strategy presents an appealing radionuclide therapy for malignant tumors., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024. Published by Elsevier B.V.)

The role of gastrin-releasing peptide receptor (GRPR) in various diseases, including cancer, has been extensively studied and has emerged as a promising therapeutic target. In this study, we successfully achieved the use of [ 212 Pb]Pb-DOTAM-GRPR1, comprising the α-particle generator, 212 Pb, combined with a GRPR-targeting peptide, GRPR1, in a prostate cancer model. Methods: Pharmacokinetics, toxicity, radiation dosimetry, and efficacy were assessed in GRPR-positive prostate tumor-bearing mice after intravenous administration of [ 212 Pb]Pb-DOTAM-GRPR1 (where DOTAM is 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane). Results: Preclinical studies have shown tumor targeting of up to 5 percent injected dose per gram over 24 h, and optimization of the drug formulation and quantity has led to minimized oxidation and off-target binding, respectively. Particularly, an increase in peptide amount from 28 to 280 ng was shown to reduce off-target uptake, especially at the level of the pancreas, by about 30%. Furthermore, dosimetry studies confirmed the kidney as the dose-limiting organ, and toxicity studies revealed that a nontoxic dose of up to 1,665 kBq could be injected into mice. Efficacy studies indicated a median survival time of 9 wk in the control group, which received only a buffer solution, compared with 19 wk in the group that received 4 injections of 370 kBq at 3-wk intervals. Conclusion: Taken together, these combined data demonstrate the safety, tolerability, and efficacy of [ 212 Pb]Pb-DOTAM-GRPR1, thus warranting further exploration in clinical trials., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

Radiotherapy is a curative arsenal for prostate cancer (PCa), but radioresistance seriously compromises its effectiveness. Dysregulated RNA splicing factors are extensively involved in tumor progression. Nonetheless, the role of splicing factors in radioresistance remains largely unexplored in PCa. Here, 23 splicing factors that are differentially expressed between PCa and adjacent normal tissues across multiple public PCa databases are identified. Among those genes, polypyrimidine tract binding protein 1 (PTBP1) is significantly upregulated in PCa and is positively associated with advanced clinicopathological features and poor prognosis. Gain- and loss-of-function experiments demonstrate that PTBP1 markedly reinforces genomic DNA stability to desensitize PCa cells to irradiation in vitro and in vivo. Mechanistically, PTBP1 interacts with the heterogeneous nuclear ribonucleoproteins (hnRNP) associated with lethal yellow protein homolog (RALY) and regulates exon 5 splicing of DNA methyltransferase 3b (DNMT3B) from DNMT3B-S to DNMT3B-L. Furthermore, upregulation of DNMT3B-L induces promoter methylation of dual-specificity phosphatase-2 (DUSP2) and subsequently inhibits DUSP2 expression, thereby increasing radioresistance in PCa. The findings highlight the role of splicing factors in inducing aberrant splicing events in response to radiotherapy and the potential role of PTBP1 and DNMT3B-L in reversing radioresistance in PCa., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Purpose: Kilovoltage cone beam computed tomography (kVCBCT)-guided adaptive radiation therapy (ART) uses daily deformed CT (dCT), which is generated automatically through deformable registration methods. These registration methods may perform poorly in reproducing volumes of the target organ, rectum, and bladder during treatment. We analyzed the registration errors between the daily kVCBCTs and corresponding dCTs for these organs using the default optical flow algorithm and two registration procedures. We validated the effectiveness of these registration methods in replicating the geometry for dose calculation on kVCBCT for ART., Methods: We evaluated three deformable image registration (DIR) methods to assess their registration accuracy and dose calculation effeciency in mapping target and critical organs. The DIR methods include (1) default intensity-based deformable registration, (2) hybrid deformable registration, and (3) a two-step deformable registration process. Each technique was applied to a computerized imaging reference system (CIRS) phantom (Model 062 M) and to five patients who received volumetric modulated arc therapy to the prostate. Registration accuracy was assessed using the 95% Hausdorff distance (HD 95 ) and Dice similarity coefficient (DSC), and each method was compared with the intensity-based registration method. The improvement in the dCT image quality of the CIRS phantom and five patients was assessed by comparing dCT with kVCBCT. Image quality quantitative metrics for the phantom included the signal-to-noise ratio (SNR), uniformity, and contrast-to-noise ratio (CNR), whereas those for the patients included the mean absolute error (MAE), mean error, peak signal-to-noise ratio (PSNR), and structural similarity index measure (SSIM). To determine dose metric differences, we used a dose-volume histogram (DVH) and 3.0%/0.3 mm gamma analysis to compare planning computed tomography (pCT) and kVCBCT recalculations with restimulated CT images used as a reference., Results: The dCT images generated by the hybrid (dCT H ) and two-step (dCT C ) registration methods resulted in significant improvements compared to kVCBCT in the phantom model. Specifically, the SNR improved by 107% and 107.2%, the uniformity improved by 90% and 75%, and the CNR improved by 212.2% and 225.6 for dCT H and dCT C methods, respectively. For the patient images, the MAEs improved by 98% and 94%, the PSNRs improved by 16.3% and 22.9%, and the SSIMs improved by 1% and 1% in the dCT H and dCT C methods, respectively. For the geometric evaluation, only the two-step registration method improved registration accuracy. The dCT H method yielded an average HD 95 of 12 mm and average DSC of 0.73, whereas dCT C yielded an average HD 95 of 2.9 mm and average DSC of 0.902. The DVH showed that the dCT C -based dose calculations differed by <2% from the expected results for treatment targets and volumes of organs at risk. Additionally, gamma indices for dCT C -based treatment plans were >95% at all points, whereas they were <95% for kVCBCT-based treatment plans., Conclusion: The two-step registration method outperforms the intensity-based and hybrid registration methods. While the hybrid and two-step-based methods improved the image quality of kVCBCT in a linear accelerator, only the two-step method improved the registration accuracy of the corresponding structures among the pCT and kVCBCT datasets. A two-step registration process is recommended for applying kVCBCT to ART, which achieves better registration accuracy for local and global image structures. This method appears to be beneficial for radiotherapy dose calculation in patients with pelvic cancer., (© 2024 The Author(s). Journal of Applied Clinical Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Background and Purpose: Fast and automated generation of treatment plans is desirable for magnetic resonance imaging (MRI)-guided adaptive radiotherapy (MRIgART). This study proposed a novel patient-specific auto-planning method and validated its feasibility in improving the existing online planning workflow., Materials and Methods: Data from 40 patients with prostate cancer were collected retrospectively. A patient-specific auto-planning method was proposed to generate adaptive treatment plans. First, a population dose-prediction model (M 0 ) was trained using data from previous patients. Second, a patient-specific model (M ps ) was created for each new patient by fine-tuning M 0 with the patient's data. Finally, an auto plan was optimized using the parameters derived from the predicted dose distribution by M ps . The auto plans were compared with manual plans in terms of plan quality, efficiency, dosimetric verification, and clinical evaluation., Results: The auto plans improved target coverage, reduced irradiation to the rectum, and provided comparable protection to other organs-at-risk. Target coverage for the planning target volume (+0.61 %, P = 0.023) and clinical target volume 4000 (+1.60 %, P < 0.001) increased. V 2900cGy (-1.06 %, P = 0.004) and V 1810cGy (-2.49 %, P < 0.001) to the rectal wall and V 1810cGy (-2.82 %, P = 0.012) to the rectum were significantly reduced. The auto plans required less planning time (-3.92 min, P = 0.001), monitor units (-46.48, P = 0.003), and delivery time (-0.26 min, P = 0.004), and their gamma pass rates (3 %/2 mm) were higher (+0.47 %, P = 0.014)., Conclusion: The proposed patient-specific auto-planning method demonstrated a robust level of automation and was able to generate high-quality treatment plans in less time for MRIgART in prostate cancer., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background and Purpose: Magnetic resonance (MR)-guided radiotherapy (MRgRT) enhances treatment precision and adaptive capabilities, potentially supporting a simulation-free (sim-free) workflow. This work reports the first clinical implementation of a sim-free workflow using the MR-Linac for prostate cancer patients treated with stereotactic ablative radiotherapy (SABR)., Materials and Methods: Fifteen patients who had undergone a prostate-specific membrane antigen positron emission tomography/CT (PSMA-PET/CT) scan as part of diagnostic workup were included in this work. Two reference plans were generated per patient: one using PSMA-PET/CT (sim-free plan) and the other using standard simulation CT (simCT plan). Dosimetric evaluations included comparisons between simCT, sim-free, and first fraction plans. Timing measurements were conducted to assess durations for both simCT and sim-free pre-treatment workflows., Results: All 15 patients underwent successful treatment using a sim-free workflow. Dosimetric differences between simCT, sim-free, and first fraction plans were minor and within acceptable clinical limits, with no major violations of standardised criteria. The sim-free workflow took on average 130 min, while the simCT workflow took 103 min., Conclusion: This work demonstrates the feasibility and benefits of sim-free MR-guided adaptive radiotherapy for prostate SABR, representing the first reported clinical experience in an ablative setting. By eliminating traditional simulation scans, this approach reduces patient burden by minimising hospital visits and enhances treatment accessibility., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [GenesisCare and Elekta AB (Stockholm, Sweden) have a strategic research agreement which includes financial support relating to the presented work]., (Crown Copyright © 2024. Published by Elsevier B.V. All rights reserved.)

Purpose: To introduce the concept of using large language models (LLMs) to relabel structure names in accordance with the American Association of Physicists in Medicine Task Group-263 standard and to establish a benchmark for future studies to reference., Methods and Materials: Generative Pretrained Transformer (GPT)-4 was implemented within a Digital Imaging and Communications in Medicine server. Upon receiving a structure-set Digital Imaging and Communications in Medicine file, the server prompts GPT-4 to relabel the structure names according to the American Association of Physicists in Medicine Task Group-263 report. The results were evaluated for 3 disease sites: prostate, head and neck, and thorax. For each disease site, 150 patients were randomly selected for manually tuning the instructions prompt (in batches of 50), and 50 patients were randomly selected for evaluation. Structure names considered were those that were most likely to be relevant for studies using structure contours for many patients., Results: The per-patient accuracy was 97.2%, 98.3%, and 97.1% for prostate, head and neck, and thorax disease sites, respectively. On a per-structure basis, the clinical target volume was relabeled correctly in 100%, 95.3%, and 92.9% of cases, respectively., Conclusions: Given the accuracy of GPT-4 in relabeling structure names as presented in this work, LLMs are poised to become an important method for standardizing structure names in radiation oncology, especially considering the rapid advancements in LLM capabilities that are likely to continue., (Copyright © 2024 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Background and Purpose: Osteopontin is a known marker for tumour hypoxia with relevance for the outcome of radiotherapy. We analysed the plasma concentration of OPN in prostate cancer patients receiving RT with or without ADT to evaluate OPN as a potential marker of treatment response., Materials and Methods: Between 2012 and 2014, 274 patients with prostate cancer qualifying for RT were enrolled to the study. SCADT received 34.3 % of patients, LCADT 46.3 %. The median OPN concentration was 83.9 ng/mL. We analysed the groups by OPN level: group A with OPN below and group B with OPN above the median., Results: There was a significant difference in OPN between the Gleason score (p = 0.005), the D'Amico risk (p = 0.002), the ADT (p < 0.001) and the RT (p = 0.019) groups. We found a positive correlation between OPN and clinical stage (p = 0.042). There were no significant effect of OPN on bRFS, RFS and MFS. The 10-year OS rate for group A was 81 % and for group B 60 % (p < 0.001). Cox analysis showed that low OPN level (p < 0.001), low age (p = 0.002) and low Gleason score (p = 0.038) were associated with higher OS. The prognostic influence of OPN on survival decreased with duration of ADT with the strongest effect of OPN (HR=3.93) observed when RT alone was used, weakest effect (HR=2.48) for SCADT and the smallest effect (HR=2.09) for LCADT., Conclusions: Based on the obtained results, we assume that the level of OPN measured before the start of radiotherapy may be an independent predictor of OS of patients with prostate cancer treated with radiotherapy with and without ADT., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Background and Purpose: Over the past decade, tools for automation of various sub-tasks in radiotherapy planning have been introduced, such as auto-contouring and auto-planning. The purpose of this study was to benchmark what degree of automation is possible., Materials and Methods: A challenge to perform automated treatment planning for prostate and prostate bed radiotherapy was set up. Participants were provided with simulation CTs and a treatment prescription and were asked to use automated tools to produce a deliverable radiotherapy treatment plan with as little human intervention as possible. Plans were scored for their adherence to the protocol when assessed using consensus expert contours., Results: Thirteen entries were received. The top submission adhered to 81.8% of the minimum objectives across all cases using the consensus contour, meeting all objectives in one of the ten cases. The same system met 89.5% of objectives when assessed with their own auto-contours, meeting all objectives in four of the ten cases. The majority of systems used in the challenge had regulatory clearance (Auto-contouring: 82.5%, Auto-planning: 77%). Despite the 'hard' rule that participants should not check or edit contours or plans, 69% reported looking at their results before submission., Conclusions: Automation of the full planning workflow from simulation CT to deliverable treatment plan is possible for prostate and prostate bed radiotherapy. While many generated plans were found to require none or minor adjustment to be regarded as clinically acceptable, the result indicated there is still a lack of trust in such systems preventing full automation., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [MJG is shareholder and director of Inpictura Ltd. TGU has institutional funding from Therapanacea for research project (completed). All remaining authors have declared no conflicts of interest]., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Purpose: To assess the early metabolic response of the primary tumor using Gallium-68 ( 68 Ga)-labeled-prostate-specific membrane antigen positron emission tomography ( 68 Ga-PSMA-PET/CT), as well as the relationship between PSMA change in the primary tumor and PSA response after definitive radiotherapy (RT), either alone or in combination with androgen deprivation therapy (ADT) in intermediate risk prostate cancer (IR-PCa) patients., Methods: The clinical data of 71 IR-PCa patients treated with RT alone (36 patients, 50.7%) or RT and ADT (35 patients, 49.3%) were retrospectively analyzed. The difference between pre- and Posttreatment primary tumor PSMA expression and serum PSA values measured 4 months after completion of treatment were compared between treatment arms. Correlation between primary tumor metabolic response and serum PSA changes was analyzed., Results: The median duration between pre- and Posttreatment 68 Ga-PSMA-PET/CT for the entire patient population was 6.9 months (range, 5.6-8.4 months), and it was similar in both treatment arms. A decrease in primary tumor maximum standardized uptake value (SUVmax) was seen in 66 patients (93.0%), with a median value of 61.2%, which is significantly lower in patients undergoing RT alone than those undergoing RT and ADT (45.1 ± 30.6% vs. 59.1 ± 24.7%; p = 0.004). The complete metabolic response rate was significantly higher in patients undergoing RT and ADT than those treated with RT alone (40% vs. 0%; p < 0.001). Although moderate and positive correlation between pretreatment SUVmax and oosttreatment SUVmax was observed, there was no significant correlation between SUV change and PSA change. For patients treated with RT and ADT, posttreatment SUVmax was significantly lower and SUV change was significantly higher in patients with PSA nadir than in those without., Conclusions: Our preliminary results show that RT, with or without ADT, significantly reduces primary tumor SUVmax and serum PSA levels. Nonetheless, our findings indicate that early treatment response using 68 Ga-PSMA-PET/CT is not feasible for those treated with RT alone, and it may only be useful in better distinguishing patients with and without PSA nadir for those who received both RT and ADT., (© 2024 The Author(s). The Prostate published by Wiley Periodicals LLC.)

Background: Electromagnetic Tracking (EMT) technology has been integrated in a prototype high-dose-rate brachytherapy (HDR-BT) afterloading device. Its potential for dwell position (DP) monitoring has earlier been demonstrated in prostate phantoms. However, its performance for prostate BT in the clinical setting remains to be assessed., Aim: Assess the reliability and value of EMT measurements in transrectal ultrasound-based (TRUS-based) and computed tomography-based (CT-based) prostate HDR-BT., Methods: EMT measurements were conducted on 20 patients undergoing dual-fraction prostate HDR-BT monotherapy. In each treatment fraction an individual TRUS-based or CT-based treatment plan was generated. The measurements were compared to DPs of manually reconstructed needles in those TRUS-based or CT-based treatment plans. An internal reference sensor was also placed in one needle to assess internal movement levels and its potential for movement correction., Results: For TRUS-based treatments, median Euclidean distances (ED) of 1.00 mm were observed between EMT measurements and manual DP determination. Reference sensor movement was minimal at a median of 0.18 mm. For DPs measured in the CT-room and treatment room, median EDs of 1.60 mm and 2.24 mm compared to CT-based DP determination respectively were observed, indicating the system's ability to detect changes in implant geometry over time and after patient repositioning. Median reference sensor movement of 0.97 mm was observed. Implementing reference sensor-based movement correction led to a significant but small decrease in ED for CT-based treatments., Conclusion: EMT is suitable for TRUS-based prostate HDR-BT quality assurance and error detection. While EMT can identify changes in implant geometry in CT-based prostate HDR-BT treatments, it showed lower accuracy in this setting., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background and Purpose: Salvage radiotherapy (SRT) is a curative treatment option in patients with biochemical recurrence after radical prostatectomy (RP). Undetectable prostate-specific antigen (PSA) < 0.1 ng/mL following SRT predicts biochemical progression-free survival (BPFS). The aim of this large retrospective study was to evaluate whether this effect persists in an extended follow-up of >5 years., Materials and Methods: A total of 678 patients treated with SRT for biochemical recurrence after RP were included. Exclusion criteria were lymph node or distant metastases, pre-SRT PSA > 3 ng/mL, and receipt of androgen deprivation therapy (ADT) between RP and SRT. All patients received a median dose of 70.2 (range 59.4-72.0) Gy to the prostatic fossa. The log-rank test (Kaplan-Meier) and Cox regression analysis were used to evaluate the impact of disease- and treatment-related parameters on BPFS, metastasis-free survival (MFS), and overall survival (OS)., Results: Median follow-up after SRT was 5.6 (range 0.1-14.5) years. The 5-year BPFS was 77.8 % in patients with a PSA nadir < 0.1 ng/mL (undetectable) and 16.3 % in the remaining cohort (p < 0.001). Five-year MFS was 95.3 % with undetectable PSA versus 84.0 % with detectable PSA (p < 0.001), and 5-year OS values were 97.5 % and 92.7 % with undetectable versus detectable PSA, respectively (p = 0.04). In multivariate analysis, undetectable PSA was the strongest predictor of BPFS (HR = 0.122; 95 %CI: 0.080-0.187; p < 0.001) and MFS (HR = 0.262; 95 %CI: 0.136-0.594; p < 0.001), but was not significant for OS (HR = 0.615; 95 %CI: 0.298-1.269; p = 0.189)., Conclusion: PSA < 0.1 ng/mL following SRT without ADT is a significant predictor of BPFS and MFS. The results suggest that it might be feasible to withhold ADT in selected patients if they have undetectable PSA after SRT. Prospective studies are warranted to confirm these findings., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

External beam radiotherapy is used for radical treatment of organ-confined prostate cancer and to treat lesions in metastatic disease whereas molecular radiotherapy with labelled prostate-specific membrane antigen ligands and radium-223 ( 223 Ra) is indicated for metastatic prostate cancer and has demonstrated substantial improvements in symptom control and overall survival compared with standard-of-care treatment. Prostate cancer is considered an immunologically cold tumour, so limited studies investigating the treatment-induced effects on the immune response have been completed. However, emerging data support the idea that radiotherapy induces an immune response in prostate cancer, but whether the response is an antitumour or pro-tumour response is dependent on the radiotherapy regime and is also cell-line dependent. In vitro data demonstrate that single-dose radiotherapy regimes induce a greater immune-suppressive profile than fractionated regimes; less is known about the immune response induced by molecular radiotherapy agents, but evidence suggests that these agents might induce an immune-suppressive systemic immune response, indicated by increased expression of inhibitory checkpoint molecules such as programmed cell death 1 ligand 1 and 2, and that these changes could be associated with clinical response. Different radiotherapy modalities can induce distinct immune profiles, which can either activate or suppress immune-mediated tumour killing and the current preclinical models used for prostate cancer research are not yet optimal for studying the complexity of the radiotherapy-induced immune response., (© 2024. Springer Nature Limited.)

Background and Purpose: A novel Cone-Beam Computed Tomography (CBCT) named HyperSight provides superior CBCT image quality compared to conventional ring gantry CBCT imaging, and it is suitable for dose calculations for prostate cancer, but it comes with considerable additional costs. The aim of this study was to determine the added value of HyperSight CBCT imaging compared to conventional CBCT imaging in terms of organ visibility in the male pelvic region., Materials and Methods: Twenty prostate cancer patients were included in this prospective clinical study. For each patient three CBCT pairs, consisting of HyperSight and conventional CBCT scans acquired on consecutive days, were included. CBCT scans were evaluated by four observers in terms of visibility of the prostate, bladder, rectum and seminal vesicles. Visibility was scored on a 1-to-5 scale and by annotating axial slices where the organs were hard to delineate. Lastly, observers indicated whether the CBCT scans were of sufficient quality for an online adaptive radiation therapy workflow., Results: All four organs were better visible on HyperSight CBCT scans compared to conventional CBCT scans. The mean visibility scores increased from 3.1 to 4.5 on a 1--5 scale of and the mean number of annotated slices reduced from 4.5 to 1.1. 99% Of the HyperSight CBCT scans were considered suitable for an online adaptive workflow vs 25-83% for the conventional CBCT scans., Conclusion: HyperSight CBCT scans yielded a visibility of prostate, bladder, rectum and seminal vesicles comparable to planning CT scans and, can replace a repeat planning CT scan in case of anatomical changes requiring a new treatment plan., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: The department of radiotherapy has research collaborations with Elekta AB, Stockholm, Sweden, Accuray Inc., Sunnyvale, CA, USA and Varian, Palo Alto, CA, USA. The current research was not funded by Varian., (Copyright © 2024. Published by Elsevier B.V.)

Objectives: This study aims to evaluate the efficacy of local treatment (LT), including radiotherapy (RT) and cytoreductive prostatectomy (CRP), in improving outcomes for patients with oligometastatic prostate cancer (OmPCa)., Methods: A systematic review and meta-analysis of articles from PubMed, Embase, and Web of Science published between 2010 and November 2023 were conducted. The study included 11 articles, comprising three randomized controlled trials (RCTs) and eight retrospective analyses. The study assessed overall survival (OS), radiographic progression-free survival (rPFS), prostate-specific antigen (PSA) PFS, cancer-specific survival (CSS), and complication rate (CR)., Results: OS was significantly improved in the LT group, with both RCTs and non-RCTs showing statistical significance [hazard ratios (HR) = 0.64; 95% confidence intervals (95% CIs), 0.51-0.80; p < 0.0001; HR = 0.55; 95% CIs, 0.40-0.77; p = 0.0004]. For rPFS, RCTs did not show statistically significant outcomes (HR = 0.60; 95% CIs, 0.34-1.07; p = 0.09), whereas non-RCTs demonstrated significant results (HR = 0.42; 95% CIs, 0.24-0.72; p = 0.002). Both RCTs and non-RCTs showed a significant improvement in PSA-PFS (HR = 0.44; 95%CI, 0.29-0.67; p = 0.0001; HR = 0.51; 95% CIs, 0.32-0.81; p = 0.004). For CSS, RCTs demonstrated statistical differences (HR = 0.65; 95% CIs, 0.47-0.90; p = 0.009), whereas non-RCTs did not (HR = 0.61; 95% CIs, 0.29-1.27; p = 0.19). Regarding CR, the risk difference was -0.22 (95% CIs, -0.32 to -0.12; p < 0.00001)., Conclusion: LT significantly improved OS and PFS in patients with OmPCa. Further RCTs are necessary to confirm these results., (© 2024 The Japanese Urological Association.)

Purpose: To reduce the rectal radiation dose during local radiation therapy of prostate cancer, a hydrogel spacer is typically implanted between the prostate and rectum. However, the spacer volume can change during external beam radiation therapy (EBRT). Therefore, we used magnetic resonance imaging (MRI) to determine changes in the spacer volume during EBRT and analyzed the data to identify patient factors influencing this change., Materials and Methods: A hydrogel spacer was implanted in each enrolled patient diagnosed with prostate cancer (n = 22, age = 69-86 years) for EBRT with a total dose of 70 Gy over 35 fractions. T2-weighted MRI images were acquired before (median = 8 days) and during EBRT, when the radiation dose of 48 Gy (median) was given at 55 days (median) after implantation. MRI images were used to determine the spacer volume as well as the maximum and minimum distances between the prostate and anterior wall of the rectum at the middle height of the prostate. Scatterplots were created to determine whether correlations existed between changes in the spacer volume and these two distances, while uni- and multivariate analyses were conducted to determine if the spacer volume change was influenced by the following patient factors: age, body mass index, estimated glomerular filtration rate, and visceral fat areas at the umbilical and femoral head positions., Results: The spacer volume increased in all 22 patients, with the smaller spacer volume before EBRT increasing by a larger amount during EBRT. This increase in the spacer volume was unaffected by other patient factors. However, it correlated with the change in the maximum distance between the prostate and anterior wall of the rectum., Conclusion: To avoid adverse changes in the rectal radiation dose during EBRT, hydrogel spacer volume should be monitored, especially if the pre-EBRT volume is small., (© 2024. The Author(s).)

Background: Prostate cancer (PCa) is a highly heterogeneous disease, making tailored treatment approaches challenging. Magnetic resonance imaging (MRI), notably diffusion-weighted imaging (DWI) and the derived Apparent Diffusion Coefficient (ADC) maps, plays a crucial role in PCa characterization. In this context, radiomics is a very promising approach able to disclose insights from MRI data. However, the sensitivity of radiomic features to MRI settings, encompassing DWI protocols and multicenter variations, requires the development of robust and generalizable models., Purpose: To develop a comprehensive radiomics framework for noninvasive PCa characterization using ADC maps, focusing on identifying reliable imaging biomarkers against intra- and inter-institution variations., Materials and Methods: Two patient cohorts, including an internal cohort (118 PCa patients) used for both training (75%) and hold-out testing (25%), and an external cohort (50 PCa patients) for independent testing, were employed in the study. DWI images were acquired with three different DWI protocols on two different MRI scanners: two DWI protocols acquired on a 1.5-T scanner for the internal cohort, and one DWI protocol acquired on a 3-T scanner for the external cohort. One hundred and seven radiomics features (i.e., shape, first order, texture) were extracted from ADC maps of the whole prostate gland. To address variations in DWI protocols and multicenter variability, a dedicated pipeline, including two-way ANOVA, sequential-feature-selection (SFS), and ComBat features harmonization was implemented. Mann-Whitney U-tests (α = 0.05) were performed to find statistically significant features dividing patients with different tumor characteristics in terms of Gleason score (GS) and T-stage. Support-Vector-Machine models were then developed to predict GS and T-stage, and the performance was assessed through the area under the curve (AUC) of receiver-operating-characteristic curves., Results: Downstream of ANOVA, two subsets of 38 and 41 features stable against DWI protocol were identified for GS and T-stage, respectively. Among these, SFS revealed the most predictive features, yielding an AUC of 0.75 (GS) and 0.70 (T-stage) in the hold-out test. Employing ComBat harmonization improved the external-test performance of the GS model, raising AUC from 0.72 to 0.78., Conclusion: By incorporating stable features with a harmonization procedure and validating the model on an external dataset, model robustness, and generalizability were assessed, highlighting the potential of ADC and radiomics for PCa characterization., (© 2024 The Author(s). Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Purpose: The occurrence of genitourinary (GU) toxicity is a common adverse event observed after external beam radiation therapy (EBRT) for prostate cancer (PCa). Recent findings suggest that the dose delivered to specific urinary organs at risk (OARs) such as the ureters, bladder trigone, and urethra is involved in the development of GU toxicity., Methods and Materials: A multidisciplinary task force including 3 radiation oncologists, a uroradiologist, and a urologist was created in 2022. First, OARs potentially involved in GU toxicity were identified and discussed. A literature review was performed, addressing several questions relative to urinary OARs: anatomic and radiological definition, radiation-induced injury, and dose-volume parameters. Second, results were presented and discussed with a panel of radiation oncologists and members of the "Francophone Group of Urological Radiation Therapy." Thereafter, the "Francophone Group of Urological Radiation Therapy" experts were asked to answer a dedicated questionnaire, including 35 questions on the controversial issues related to the delineation of urinary OARs., Results: The following structures were identified as critical for PCa EBRT: ureters, bladder, bladder neck, bladder trigone, urethra (intraprostatic, membranous, and spongious), striated sphincter, and postenucleation or posttransurethral resection of the prostate cavity. A consensus was obtained for 32 out of 35 items., Conclusions: This consensus highlights contemporary urinary structures in both the upper and lower urinary tract to be considered for EBRT treatment planning of PCa. The current recommendations also propose a standardized definition of urinary OARs for both daily practice and future clinical trials., Competing Interests: Disclosures None., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: The aim of this study is to research the value of the texture analysis of primary tumors in pre-treatment [68Ga]Ga-PSMA PET in the prediction of the development of biochemical recurrence (BCR) in prostate cancer patients who underwent definitive therapies., Methods: 51 patients with prostate adenocarcinoma who had a pre-treatment [68Ga]Ga-PSMA-11 PET/CT and underwent definitive radiotherapy (RT) or radical prostatectomy (RP) were included in the study. Demographics, clinicopathologic features, the presence of BCR, and the last follow-up date of patients were recorded. Textural and conventional PET parameters (maximum standardized uptake value (SUVmax), total lesion-PSMA (TL-PSMA), and PSMA-tumor volume (PSMA-TV)) were obtained from PET/CT images using LifeX program. Parameters were grouped using the Youden index in ROC analysis. Factors predicting the BCR were determined using Cox regression analyses., Results: 29 (56.9%) patients have received primary curative RT, while the remaining 22 (43.1%) patients have undergone RP. 5 (22.7%) patients with RP and 3 (10.3%) patients with curative RT have developed BCR during the follow-up. INTENSITY-BASED-minimum grey level (P=.050), GLCM-sum variance (P=.019), and GLCM-cluster prominence (P=.050) were associated with BCR in univariate analysis. INTENSITY-BASED-minimum grey level (P=.009) and GLCM-sum variance (P=.004) were found as independent predictors of BCR in the multivariate analysis., Conclusion: Tumor heterogeneity on pre-treatment [68Ga]Ga-PSMA PET is associated with a high risk of BCR in PCa patients who underwent definitive therapies., (Copyright © 2024 Sociedad Española de Medicina Nuclear e Imagen Molecular. Published by Elsevier España, S.L.U. All rights reserved.)

Purpose: Hypoxia in tumors is associated with increased malignancy and resistance to conventional photon radiation therapy. This study investigated the potential of particle therapy to counteract radioresistance in syngeneic rat prostate carcinoma., Methods and Materials: Subcutaneously transplanted R3327-HI tumors were irradiated with photons or carbon ions under acute hypoxic conditions, induced by clamping the tumor-supplying artery 10 min before and during irradiation. Dose-response curves were determined for the endpoint "local tumor control within 300 days" and compared with previously published data acquired under oxic conditions. Doses at 50% tumor control probability (TCD 50 ) were used to quantify hypoxia-induced radioresistance relative to that under oxic conditions and also to quantify the increased effectiveness of carbon ions under oxic and hypoxic conditions relative to photons., Results: Compared with those under oxic conditions, TCD 50 values under hypoxic conditions increased by a factor of 1.53 ± 0.08 for photons and by a factor of 1.28 ± 0.06 for carbon ions (oxygen enhancement ratio). Compared with those for photons, TCD 50 values for carbon ions decreased by a factor of 2.08 ± 0.13 under oxic conditions and by a factor of 2.49 ± 0.08 under hypoxic conditions (relative biological effectiveness). While the slope of the photon dose-response curves increased when changing from oxic to hypoxic conditions, the slopes were steeper and remained unchanged for carbon ions., Conclusions: The reduced oxygen enhancement ratio of carbon ions indicated that the required dose increase in hypoxic tumors was 17% lower for carbon ions than for photons. Additionally, carbon ions reduced the effect of intertumor heterogeneity on the radiation response. Therefore, carbon ions may confer a significant advantage for the treatment of hypoxic tumors that are highly resistant to conventional photon radiation therapy., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objective: To explore the optimal timing for placing an artificial urinary sphincter (AUS) postradiation therapy (RT)., Methods: A bi-institutional retrospective review of all patients who underwent their first (virgin) AUS placement after pelvic RT between January 1, 2011 and July 1, 2023. To determine the optimal timeline for device implantation 2-5years post-RT, we compared hazard ratios for device revision/explantation (Rev/Exp) using Kaplan-Meier curves for each year (earlier vs later than 2/3/4/5 years post-RT). The Pearson correlation coefficient identified trends in Rev/Exp reasons (erosion/infection vs other)., Results: Seventy-two patients met our inclusion criteria with a median age of 65.5years (interquartile range 70-81.25). Fifteen (20.8%) had undergone one or more previous urethral or bladder neck interventions (urethroplasty in 1 [1.4%], internal urethrotomy in 7 [9.7%], and bladder neck incision in 9 [12.5%]). After a median follow-up of 57.5months (interquartile range 13-107), a total of 36 (50%) devices were Rev/Exp, with mechanical failure in 14 (19.4%) and device erosion in 12 (16.7%) being the main reasons. Device survival analysis revealed no significant difference in the risk of device Rev/Exp when implanted earlier vs later than 2, 3, 4, or 5years post-RT, with P-values of .3, .3, .4, and .4, respectively. A constant trend toward higher infection/erosion rates as indication for device Rev/Exp the later the insertion was noticed: R 2 = 0.98., Conclusion: Despite a small sample size, our study indicates that implanting an AUS within 5 years after RT shows comparable device lifespan. However, later insertions may have higher removal rates due to erosion/infection., Clinical Trial Registration: Not applicable., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to declare., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: In 2021, the tubarial salivary glands (TSGs) were newly identified on prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) as macroscopic glands in the nasopharyngeal wall. However, the relative contribution of the TSGs to the total salivary gland function, and consequently on the development of xerostomia after external beam radiotherapy (EBRT) or PSMA-targeted radionuclide therapy (RNT) is not known. Therefore, we aimed to determine the presence of the TSGs and to quantify uptake in the TSGs on PSMA PET., Methods: Qualitative and quantitative analyses were performed on 68 Ga-PSMA-11 PET/CT scans of 100 patients with prostate cancer. The mean and maximum standardized uptake value (SUVmean and SUVmax) in the TSGs were measured and compared to the parotid, submandibular and sublingual salivary glands (PSGs, SMSGs and SLSGs, respectively). Furthermore, proportional function of the TSGs was compared to the PSGs, SMSGs and SLSGs based on the total organ PSMA (TO-PSMA)., Results: The TSGs were visible on 95% of the 68 Ga-PSMA-11 PET/CT scans. The normalized median SUVmean and SUVmax was significantly higher for the PSGs (p < 0.001) and SMSGs (p < 0.001) compared to the TSGs, but not for the SLSGs (p = 0.242 and p = 0.300, respectively). The normalized median TO-PSMA was significantly higher for the PSGs (p < 0.001) and SMSGs (p < 0.001), and significant lower for the SLSGs (p < 0.001) compared the TSGs., Conclusions: The SUVmean, SUVmax and TO-PSMA of the TSGs were most comparable to the SLSGs. However, the measured PSMA uptake may be disproportional towards the saliva production. Therefore, future studies should focus on the relation between PSMA uptake and salivary function before and after PSMA therapy., (© 2024. The Author(s).)

Purpose: To provide a comprehensive review of the means by which to optimize target volume definition for the purposes of treatment planning for patients with intact prostate cancer with a specific emphasis on focal boost volume definition., Methods: Here we conduct a narrative review of the available literature summarizing the current state of knowledge on optimizing target volume definition for the treatment of localized prostate cancer., Results: Historically, the treatment of prostate cancer included a uniform prescription dose administered to the entire prostate with or without coverage of all or part of the seminal vesicles. The development of prostate magnetic resonance imaging (MRI) and positron emission tomography (PET) using prostate-specific radiotracers has ushered in an era in which radiation oncologists are able to localize and focally dose-escalate high-risk volumes in the prostate gland. Recent phase 3 data has demonstrated that incorporating focal dose escalation to high-risk subvolumes of the prostate improves biochemical control without significantly increasing toxicity. Still, several fundamental questions remain regarding the optimal target volume definition and prescription strategy to implement this technique. Given the remaining uncertainty, a knowledge of the pathological correlates of radiographic findings and the anatomic patterns of tumor spread may help inform clinical judgement for the definition of clinical target volumes., Conclusion: Advanced imaging has the ability to improve outcomes for patients with prostate cancer in multiple ways, including by enabling focal dose escalation to high-risk subvolumes. However, many questions remain regarding the optimal target volume definition and prescription strategy to implement this practice, and key knowledge gaps remain. A detailed understanding of the pathological correlates of radiographic findings and the patterns of local tumor spread may help inform clinical judgement for target volume definition given the current state of uncertainty., Competing Interests: Disclosures Uulke van der Heide has collaborative agreements with Elekta AB and Philips; received grants from the Dutch Cancer Society and travel funding from Elekta AB; and is a member of the ASTRO Scientific Council. Linda Kerkmeijer received honoraria from SIU (2021), VenVN (2021), and the Dutch guideline committee renal cell carcinoma by SKMS; received travel stipend from ESTRO (2022); is a board member of the Dutch Uro-Oncology study group. Baris Turkbey received royalties from the National Institutes of Health; has multiple patents in AI (details available on request); has cooperative research and development agreements with NVIDIA and Philips. William Hall received consulting fees from Aktis oncology; received honoraria from Elekta; received travel funding from Elekta; serves a position as the Vice Chair of the MR Linac Consortium Steering Committee. Provisional Patient 63/483,252 was filed by the institution on medical devices to assess radiation readiness. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Published by Elsevier Inc.)

Purpose: Whole-pelvis (WP) radiation therapy (radiation) improved biochemical relapse-free survival (bRFS) compared with prostate bed (PB)-only radiation in the Radiation Therapy Oncology Group 0534, but was performed in an era prior to positron emission tomography (PET) staging. Separately, 18F-fluciclovine PET/CT-guided postprostatectomy radiation improved 3-year bRFS versus radiation guided by conventional imaging alone. We hypothesized that patients who were changed from WP to PB-only radiation after PET would have bRFS that was: (a) no higher than patients initially planned for PB-only radiation; and (b) lower than patients planned for WP radiation without PET guidance., Methods and Materials: We conducted a post hoc analysis of a prospective, randomized trial comparing conventional (arm 1) versus PET-guided (arm 2) postprostatectomy radiation. In arm 2, pre-PET treatment field decisions were recorded and post-PET fields were defined per protocol; pathologic node negative (pN0) without pelvic or extrapelvic PET uptake received PB-only radiation. Three-year bRFS was compared in patients planned for WP with change to PB-only radiation (arm 2 [WP:PB]) vs arm 2 patients planned for PB-only with final radiation to PB-only (arm 2 [PB:PB]) and arm 1 pN0 patients treated with WP radiation (arm 1 [WP]) using the Z test and log-rank test. Demographics were compared using the chi-square test, Fisher exact test, or analysis of variance, as appropriate., Results: We identified 10 arm 2 (WP:PB), 31 arm 2 (PB:PB) and 11 arm 1 (WP) patients. Androgen deprivation was used in 50.0% of arm 2 (WP:PB) and 3.2% of arm 2 (PB:PB) patients, P < .01. Median preradiation prostate-specific antigen was higher in arm 2 (WP:PB) vs arm 2 (PB:PB) patients (0.4 vs 0.2 ng/mL, P = .03); however, there were no significant differences in T stage, Gleason score, or margin positivity. Three-year bRFS was 80% in arm 2 (WP:PB) vs 87.4% in arm 2 (PB:PB), P = .47, respectively. Arm 1(WP) patients had significantly worse 3-year (23%) bRFS vs arm 2 (WP:PB), P < .01., Conclusions: Patients initially planned for WP radiation with field decision change to PB-only radiation after PET showed (1) no significant difference in 3-year bRFS compared with patients initially planned for PB-only radiation; and (2) improved bRFS compared with patients receiving WP radiation without PET guidance. PET-guided volume de-escalation in selected patients may be 1 approach to mitigating toxicity without compromising outcomes., (Copyright © 2024 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Background: The risk of cardiac disease mortality has recently become a focal point of concern within the medical community for patients with prostate cancer (PCa). Given that radical prostatectomy (RP) and external beam radiation therapy (EBRT) are the main treatment modalities for localized PCa, their specific impact on cardiovascular-specific mortality (CSM) remains unclear. This study explored the specific effects of RP and EBRT on CSM risk to guide clinical treatment decisions., Methods: Data from patients aged 45-74 years, who were diagnosed with T1-2N0M0 stage PCa from the SEER database (2010-2015), were used. Multivariate statistical methods, including propensity score matching (PSM), competing risk regression, COX regression analysis, and Fine-Gray testing, were applied to assess the impact of RP and EBRT on CSM risk., Results: Among 146,082 T1-2 stage PCa patients, cardiac disease emerged as the primary cause of death, surpassing PCa itself. Multifactorial COX regression and competing risk regression analyses indicated that local treatments do not increase CSM risk. Further analysis revealed a significant increase in CSM risk for patients undergoing only EBRT compared with those undergoing only RP (hazard ratio [HR]  = 2.71, 95% confidence interval [CI] 1.96-3.74, P < 0.001), with subsequent PSM adjustment, further confirming a significantly reduced risk in the RP treatment group (HR 0.23, 95% CI 0.13-0.40, P < 0.001)., Conclusions: T1-2 stage PCa patients face a significant risk of CSM, with RP offering a potential advantage over EBRT in reducing this risk. These findings encourage clinicians to comprehensively consider the potential impact on cardiac health when formulating treatment plans, providing crucial guidance for optimizing treatment strategies., (© 2024. Society of Surgical Oncology.)

Purpose: Until March 2018, patients with high-risk localized prostate cancer had been administered high-dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy (EBRT) without additional hormone therapy (HT) at our institution. In this study, we aimed to evaluate long-term outcomes of this treatment., Materials and Methods: Patients with prostate cancer who received HDR-BT and EBRT between April 1997 and March 2021 and who were followed up for at least 6 months were included in the study. High-risk groups were classified into five levels according to the National Comprehensive Cancer Network guidelines. The EBRT and HDR-BT doses were 39-45 Gy/13-25 fractions. and 16.5-22 Gy/2-4 fractions, respectively. None of the patients received HT during initial treatment. The Kaplan-Meier method was used to estimate biochemical freedom from failure (bFFF), cause-specific survival (CSS), and overall survival (OS) rates. Biochemical failure was also determined., Results: Seventy-two patients were enrolled in the study, with a median follow-up of 91.9 months. The median age and initial prostate-specific antigen (iPSA) level were 71 years and 10.95 ng/mL, respectively. The median biologically effective dose for HDR-BT plus EBRT was 270.3 Gy. The 5- and 7-year bFFF, CSS, and OS rates were 85.2 and 74.2%, 100 and 100%, and 95.7 and 91.9%, respectively. Only the iPSA ≤ 20 group was associated with the higher bFFF rate. The 7-year bFFF rates in the groups with iPSA ≤ 20 and iPSA > 20 were 86.6 and 48.6%, respectively., Conclusion: HDR-BT plus EBRT without HT might be an alternative treatment option for patients with high-risk localized prostate cancer and iPSA levels ≤ 20. Further studies are required to validate the efficacy of this treatment strategy., (© 2024. The Author(s).)

Background: Daily adaptive radiotherapy, as performed with the Elekta Unity MR-Linac, requires choosing between different adaptation methods, namely ATP (Adapt to Position) and ATS (Adapt to Shape), where the latter requires daily re-contouring to obtain a dose plan tailored to the daily anatomy. These steps are inherently resource-intensive, and quickly predicting the dose distribution and the dosimetric evaluation criteria while the patient is on the table could facilitate a fast selection of adaptation method and decrease the treatment times., Purpose: In this work, we aimed to develop a deep-learning-based dose-prediction pipeline for prostate MR-Linac treatments., Methods: Two hundred twelve MR-images, structure sets, and dose distributions from 35 prostate patients treated with 6.1 Gy for 7 or 6 fractions at our MR-Linac were included, split into train/test partitions of 152/60 images, respectively. A deep-learning segmentation network was trained to segment the CTV (prostate), bladder, and rectum. A second network was trained to predict the dose distribution based on manually delineated structures. At inference, the predicted segmentations acted as input to the dose prediction network, and the predicted dose was compared to the true (optimized in the treatment planning system) dose distribution., Results: Median DSC values from the segmentation network were 0.90/0.94/0.87 for CTV/bladder/rectum. Predicted segmentations as input to the dose prediction resulted in mean differences between predicted and true doses of 0.7%/0.7%/1.7% (relative to the prescription dose) for D 98% /D 95% /D 2% for the CTV. For the bladder, the difference was 0.7%/0.3% for D mean /D 2% and for the rectum 0.1/0.2/0.2 pp (percentage points) for V 33Gy /V 38Gy /V 41Gy . In comparison, true segmentations as input resulted in differences of 1.1%/0.9%/1.6% for CTV, 0.5%/0.4% for bladder, and 0.7/0.4/0.3 pp for the rectum. Only D 2% for CTV and D mean /D 2% for bladder were found to be statistically significantly better when using true structures instead of predicted structures as input to the dose prediction., Conclusions: Small differences in the fulfillment of clinical dose-volume constraints are seen between utilizing deep-learning predicted structures as input to a dose prediction network and manual structures. Overall mean differences <2% indicate that the dose-prediction pipeline is useful as a decision support tool where differences are >2%., (© 2024 The Author(s). Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

This retrospective, multi-centered study aimed to improve high-quality radiation treatment (RT) planning workflows by training and testing a Convolutional Neural Network (CNN) to perform auto segmentations of organs at risk (OAR) for prostate cancer (PCa) patients, specifically the bladder and rectum. The objective of this project was to develop a clinically applicable and robust artificial intelligence (AI) system to assist radiation oncologists in OAR segmentation. The CNN was trained using manual contours in CT-datasets from diagnostic 68 Ga-PSMA-PET/CTs by a student, then validated (n = 30, PET/CTs) and tested (n = 16, planning CTs). Further segmentations were generated by a commercial artificial intelligence (cAI) software. The ground truth were manual contours from expert radiation oncologists. The performance was evaluated using the Dice-Sørensen Coefficient (DSC), visual analysis and a Turing test. The CNN yielded excellent results in both cohorts and OARs with a DSC median  > 0.87, the cAI resulted in a DSC > 0.78. In the visual assessment, 67% (bladder) and 75% (rectum) of the segmentations were rated as acceptable for treatment planning. With a misclassification rate of 45.5% (bladder) and 51.1% (rectum), the CNN passed the Turing test. The metrics, visual assessment and the Turing test confirmed the clinical applicability and therefore the support in clinical routine., (© 2024. The Author(s).)

Background: The other side of radiotherapy (RT), in addition to the cytotoxic effect, is the ability to modulate the immune system in terms of activation or suppression, also depending on the dose and fractionation delivered. This immune RT effect can be detected both locally in the irradiated tumor site and in the peripheral blood. The aim of this study was to assess the consequence of pelvic irradiation on peripheral immune cells and cytokine secretions in localized prostate cancer (PC) patients undergoing pelvic irradiation with a simultaneous moderately hypofractionated prostate/prostate bed boost by Volumetric Modulated Arc Therapy (VMAT). Furthermore, we analyzed whether there was a correlation between these peripheral immune parameters and acute and late genitourinary (GU) and gastrointestinal (GI) toxicity., Methods: Thirty-eight PC patients were treated with pelvis irradiation (dose per fraction 1.8 Gy) and simultaneous hypofractionated (median dose per fraction: 2.7 Gy) prostate/prostate bed boost. A longitudinal analysis was performed for 12 months on peripheral blood to assess changes in 9 different lymphocyte subpopulations by flow cytometry and 10 circulating cytokines by Multiplex Luminex assay and ELISA., Results: Our analysis revealed that basal IFN-γ serum values were significantly lower in the definitive (curative intent for patients with prostate) patient group respect to the post-operative one. All the lymphocyte subsets and IFN-α, IFN-β and Il-2 peripheral concentrations displayed significant variations between the different time points considered. The immune cell population that suffers the greatest RT toxicity in the blood was B lymphocyte. We found an interesting correlation between basal TGF-β1 and late GU toxicity. In particular, TGF-β1 concentrations before RT were significantly higher in patients that experienced grade 2-3 of late GU toxicity, respect to grade 0-1. Exploring possible correlations between some clinical/biological findings and radiation planning parameters, we found no statistical significance., Conclusions: Our study analyzed, in the context of hypofractionated radiotherapy in prostate cancer, different parameters of the peripheral immune system. We have highlighted longitudinally the peripheral behavior of the different lymphocyte subpopulations and of a group of 10 cytokines during the first year after RT. One of the analyzed cytokines, such as TGF-β1, has proven to be promising predictive factor of severe late GU toxicity., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 D’Auria, Valvano, Calice, D’Esposito, Cabaro, Formisano, Bianchino, Traficante, Bianculli, Lazzari, Statuto and Rago.)

Objective. To present a long short-term memory (LSTM) network-based dose calculation method for magnetic resonance (MR)-guided proton therapy. Approach. 35 planning computed tomography (CT) images of prostate cancer patients were collected for Monte Carlo (MC) dose calculation under a perpendicular 1.5 T magnetic field. Proton pencil beams (PB) at three energies (150, 175, and 200 MeV) were simulated (7560 PBs at each energy). A 3D relative stopping power cuboid covering the extent of the PB dose was extracted and given as input to the LSTM model, yielding a 3D predicted PB dose. Three single-energy (SE) LSTM models were trained separately on the corresponding 150/175/200 MeV datasets and a multi-energy (ME) LSTM model with an energy embedding layer was trained on either the combined dataset with three energies or a continuous energy (CE) dataset with 1 MeV steps ranging from 125 to 200 MeV. For each model, training and validation involved 25 patients and 10 patients were for testing. Two single field uniform dose prostate treatment plans were optimized and recalculated with MC and the CE model. Results. Test results of all PBs from the three SE models showed a mean gamma passing rate (2%/2 mm, 10% dose cutoff) above 99.9% with an average center-of-mass (COM) discrepancy below 0.4 mm between predicted and simulated trajectories. The ME model showed a mean gamma passing rate exceeding 99.8% and a COM discrepancy of less than 0.5 mm at the three energies. Treatment plan recalculation by the CE model yielded gamma passing rates of 99.6% and 97.9%. The inference time of the models was 9-10 ms per PB. Significance. LSTM models for proton dose calculation in a magnetic field were developed and showed promising accuracy and efficiency for prostate cancer patients., (Creative Commons Attribution license.)

Background: Whether stereotactic body radiotherapy (SBRT) is noninferior to conventionally or moderately hypofractionated regimens with respect to biochemical or clinical failure in patients with localized prostate cancer is unclear., Methods: We conducted a phase 3, international, open-label, randomized, controlled trial. Men with stage T1 or T2 prostate cancer, a Gleason score of 3+4 or less, and a prostate-specific antigen (PSA) level of no more than 20 ng per milliliter were randomly assigned (in a 1:1 ratio) to receive SBRT (36.25 Gy in 5 fractions over a period of 1 or 2 weeks) or control radiotherapy (78 Gy in 39 fractions over a period of 7.5 weeks or 62 Gy in 20 fractions over a period of 4 weeks). Androgen-deprivation therapy was not permitted. The primary end point was freedom from biochemical or clinical failure, with a critical hazard ratio for noninferiority of 1.45. The analysis was performed in the intention-to-treat population., Results: A total of 874 patients underwent randomization at 38 centers (433 patients in the SBRT group and 441 in the control radiotherapy group) between August 2012 and January 2018. The median age of the patients was 69.8 years, and the median PSA level was 8.0 ng per milliliter; the National Comprehensive Cancer Network risk category was low for 8.4% of the patients and intermediate for 91.6%. At a median follow-up of 74.0 months, the 5-year incidence of freedom from biochemical or clinical failure was 95.8% (95% confidence interval [CI], 93.3 to 97.4) in the SBRT group and 94.6% (95% CI, 91.9 to 96.4) in the control radiotherapy group (unadjusted hazard ratio for biochemical or clinical failure, 0.73; 90% CI, 0.48 to 1.12; P = 0.004 for noninferiority), which indicated the noninferiority of SBRT. At 5 years, the cumulative incidence of late Radiation Therapy Oncology Group (RTOG) grade 2 or higher genitourinary toxic effects was 26.9% (95% CI, 22.8 to 31.5) with SBRT and 18.3% (95% CI, 14.8 to 22.5) with control radiotherapy (P<0.001), and the cumulative incidence of late RTOG grade 2 or higher gastrointestinal toxic effects was 10.7% (95% CI, 8.1 to 14.2) and 10.2% (95% CI, 7.7 to 13.5), respectively (P = 0.94)., Conclusions: Five-fraction SBRT was noninferior to control radiotherapy with respect to biochemical or clinical failure and may be an efficacious treatment option for patients with low-to-intermediate-risk localized prostate cancer as defined in this trial. (Funded by Accuray and others; PACE-B ClinicalTrials.gov number, NCT01584258.)., (Copyright © 2024 Massachusetts Medical Society.)

Radiotherapy represents a major curative treatment for prostate cancer (PCa), but some patients will develop radioresistance (RR) and relapse. The underlying mechanisms remain poorly understood, and miRNAs might be key players in the acquisition and maintenance of RR. Through their encapsulation in small extracellular vesicles (EVs), they can also be relevant biomarkers of radiation response. Using next-generation sequencing, we found that miR-200c-3p was downregulated in PCa RR cells and in their small EVs due to a gain of methylation on its promoter during RR acquisition. We next showed that its exogenous overexpression restores the radiosensitivity of RR cells by delaying DNA repair through the targeting of HP1α. Interestingly, we also observed downregulation of miR-200c-3p expression by DNA methylation in radiation-resistant lung and breast cancer cell lines. In summary, our study demonstrates that the downregulation of miR-200c-3p expression in PCa cells and in their small EVs could help distinguish radioresistant from sensitive tumor cells. This miRNA targets HP1α to delay DNA repair and promote cell death., (© 2024. The Author(s).)

Ras homolog gene family member C (RhoC) is a GTPase involved in cell migration, implicated in epithelial-mesenchymal transition and treatment resistance and metastasis of cancer. For example, RhoC has been shown to be involved in resistance to radiation in cervical carcinoma. Here, the effect of X-ray irradiation on RhoC expression in prostate cancer (PCa) xenografts was investigated in both xenografts in regression and relapse. Male BALB/cAnNRj-Foxn1 nu/nu mice were inoculated with 4-6 million LNCaP-FGC cells and established xenografts were irradiated with X-rays (200 kV, 1 Gymin -1 ), 5, 10 or 15 Gy using a Gulmay Medical X-ray system. Expression of RhoC and Ki67, a known proliferation marker, was investigated in xenografts, given 15 Gy, 7 days (midst response as measured by size) or 3 weeks (relapse) post irradiation. Staining was quantified using the Halo software (v2.3.2089.34) with the Indica Labs - cytonuclear v1.6 algorithm. RhoC and Ki67 staining was divided into weak, medium, and strong staining and the percentage of cells stained, single and dual staining, was quantified. The HALO software was further used to classify the tissue in each section so that analysis of RhoC and Ki67 expression in cancer cells, stroma and necrotic areas could be done separately. The results showed that RhoC expression in cancer and stroma cells was significantly higher in relapsed xenografts than in those in regression. This was not seen for Ki67 staining, where the percentage of stained cells were the same in regressing and relapsing tumors. RhoC could be a useful biomarker to confirm relapse following external beam radiation therapy., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Oskar Vilhelmsson Timmerand reports financial support was provided by RhoVac Aps. Jens Ceder reports financial support was provided by RhoVac Aps. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective. Relative biological effectiveness (RBE) differs between radiation qualities. However, an RBE of 1.0 has been established for photons regardless of the wide range of photon energies used clinically, the lack of reproducibility in radiobiological studies, and outdated reference energies used in the experimental literature. Moreover, due to intrinsic radiosensitivity, different cancer types have different responses to radiation. This study aimed to characterize the RBE of clinically relevant high and low photon energies in vitro for three human cancer cell lines: HCT116 (colon), HeLa (cervix), and PC3 (prostate). Approach. Experiments were conducted following dosimetry protocols provided by the American Association of Physicists in Medicine. Cells were irradiated with 6 MV x-rays, an 192 Ir brachytherapy source, 225 kVp and 50 kVp x-rays. Cell survival post-irradiation was assessed using the clonogenic assay. Survival fractions were fitted using the linear quadratic model, and survival curves were generated for RBE calculations. Main results. Cell killing was more efficient with decreasing photon energy. Using 225 kVp x-rays as the reference, the HCT116 RBE SF0.1 for 6 MV x-rays, 192 Ir, and 50 kVp x-rays were 0.89 ± 0.03, 0.95 ± 0.03, and 1.24 ± 0.04; the HeLa RBE SF0.1 were 0.95 ± 0.04, 0.97 ± 0.05, and 1.09 ± 0.03, and the PC3 RBE SF0.1 were 0.84 ± 0.01, 0.84 ± 0.01, and 1.13 ± 0.02, respectively. HeLa and PC3 cells had varying radiosensitivity when irradiated with 225 and 50 kVp x-rays. Significance. This difference supports the notion that RBE may not be 1.0 for all photons through experimental investigations that employed precise dosimetry. It highlights that different cancer types may not have identical responses to the same irradiation quality. Additionally, the RBE of clinically relevant photons was updated to the reference energy of 225 kVp x-rays., (Creative Commons Attribution license.)

Importance: The association between radiotherapy (RT) timing after radical prostatectomy and long-term patient-reported health-related quality of life (HRQOL) in men with prostate cancer is unknown., Objective: To measure long-term HRQOL in men with prostate cancer up to 15 years after prostatectomy with or without RT and examine whether early vs late postprostatectomy RT is associated with differences in sexual, urinary, and bowel HRQOL., Design, Setting, and Participants: A prospective, multicenter, longitudinal cohort analysis using HRQOL data from the PROST-QA (2003-2006) and RP2 consortium (2010-2013) studies was conducted. Men with localized prostate cancer undergoing radical prostatectomy were included. Data were analyzed between May 8, 2023, and March 1, 2024. The study was conducted in 12 high-volume academic medical centers in the US., Exposures: Men were stratified based on receipt and timing of postprostatectomy RT: prostatectomy only, early RT (<12 months), and late RT (≥12 months)., Main Outcomes and Measures: Longitudinal sexual, incontinence, urinary irritation, bowel, and hormonal/vitality HRQOL were measured via the Expanded Prostate Cancer Index Composite at baseline; months 2, 6, and 12; and annually thereafter. Treatment groups were compared using multivariable linear mixed-effects models of change in longitudinal domain scores. Pad use for incontinence was measured longitudinally among men receiving postprostatectomy RT., Results: A total of 1203 men were included in the study: prostatectomy only (n = 1082), early RT (n = 57), and late RT (n = 64). Median age for the entire cohort was 60.5 (range, 38.8-79.7) years, and 1075 men (92.0%) were White. Median follow-up was 85.6 (IQR, 35.8-117.2) months. Compared with men receiving prostatectomy alone, those receiving postprostatectomy RT had significantly greater decreases in sexual, incontinence, and urinary irritation HRQOL. However, timing of postprostatectomy RT, specifically early vs late, was not associated with a long-term decrease in any HRQOL domain. There was evidence of improved recovery of sexual, continence, and urinary irritation scores among men receiving early RT compared with those receiving late RT after prostatectomy. Before the start of postprostatectomy RT, 39.3% of men in the early RT cohort and 73.4% of men in the late RT cohort were pad-free. By the sixth visit post-RT, 67.4% in the early RT cohort and 47.6% in the late RT cohort were pad-free., Conclusions and Relevance: In this multicenter, prospective analysis, postprostatectomy RT appeared to be negatively associated with long-term HRQOL across all domains. However, receipt of early vs late postprostatectomy RT may result in similar long-term HRQOL outcomes.