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Purpose: Rates of rectal toxicity after low-dose-rate (LDR) brachytherapy for prostate cancer are dependent on rectal dose, which is associated with rectal distance from prostate and implanted seeds. Placement of a hydrogel spacer between the prostate and rectum has proven to reduce the volume of the rectum exposed to higher radiation dose levels in the setting of external beam radiotherapy. We present our findings with placing a rectal hydrogel spacer in patients following LDR brachytherapy, and we further assess the impact of this placement on dosimetry and acute rectal toxicity., Methods and Materials: Between January 2016 and April 2017, 74 patients had placement of a hydrogel spacer, immediately following a Pd-103 seed-implant procedure. Brachytherapy was delivered as follows: as a monotherapy to 26 (35%) patients; as part of planned combination therapy with external beam radiotherapy to 40 (54%) patients; or as a salvage monotherapy to eight (11%) patients. Postoperative MRI was used to assess separation achieved with rectal spacer. Acute toxicity was assessed retrospectively using Radiation Oncology Therapy Group radiation toxicity grading system. Rectal dosimetry was compared with a consecutive cohort of 136 patients treated with seed implantation at our institution without a spacer, using a 2-tailed paired Student's t test (p < 0.05 for statistical significance)., Results: On average, 11.2-mm (SD 3.3) separation was achieved between the prostate and the rectum. The resultant mean rectal volume receiving 100% of prescribed dose (V 100% ), dose to 1 cc of rectum (D 1cc ), and dose to 2 cc of rectum (D 2cc ) were 0 (SD 0.05 cc), 25.3% (SD 12.7), and 20.5% (SD 9.9), respectively. All rectal dosimetric parameters improved significantly for the cohort with spacer placement as compared with the nonspacer cohort. Mean prostate volume, prostate V 100 and dose to 90% of gland (D 90 ) were 29.3 cc (SD 12.4), 94.0% (SD 3.81), and 112.4% (SD 12.0), respectively. Urethral D 20 , D 5cc , and D 1cc were 122.0% (SD 17.27), 133.8% (SD 22.8), and 144.0% (SD 25.4), respectively. After completing all treatments, at the time of first the followup, 7 patients reported acute rectal toxicity-6 experiencing Grade 1 rectal discomfort and 1 (with preexisting hemorrhoids) experiencing Grade 1 bleeding., Conclusions: Injection of rectal spacer is feasible in the post-LDR brachytherapy setting and reduces dose to the rectum with minimal toxicity. Prostate and urethral dosimetries do not appear to be affected by the placement of a spacer. Further studies with long-term followup are warranted to assess the impact on reduction of late rectal toxicity., (Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Background: To compare chronological changes in lower urinary tract symptoms (LUTS) after low-dose-rate prostate extended-release therapy (LDR-BT) using the overactive bladder symptom score (OABSS) in patients aged ≥ 75 years (elderly group) versus those aged < 75 years (control group). Materials and Methods: Patients with prostate cancer who underwent LDR-BT at Gifu University Hospital were included in this study. The International Prostate Symptom Score (IPSS), OABSS, and quality of life-based on urinary symptoms (IPSS-QOL) were evaluated before and after LDR-BT. We compared chronological changes in IPSS, OABSS, and IPSS-QOL in the elderly group with those in the control group and assessed the association between the resolution of OABSS and clinicopathological covariates. Results: A total of 484 patients were enrolled in this study. In the elderly group, the total IPSS, OABSS, and frequency scores increased at 1 month postoperatively, whereas the control group showed an increase at 3 months postoperatively. Multivariate analysis identified changes from baseline to the maximum OABSS and pre-treatment OABSS as significant predictors of delayed resolution of OABSS after LDR-BT. Conclusions: Changes in pre-treatment OABSS and pre- and post-LDR-BT OABSS values were independent predictors of delayed resolution of OABSS; however, no correlation was found with age. [ABSTRACT FROM AUTHOR]

Objective: Higher quality of postimplant dosimetric evaluation is associated with higher biochemical recurrence‐free survival rates after low‐dose‐rate brachytherapy for localized prostate cancer. Postimplant prostate D90 is a key dosimetric parameter showing the quality of low‐dose‐rate brachytherapy. In this study, to improve the quality of low‐dose‐rate brachytherapy for localized prostate cancer, we investigated pre‐implant factors affecting the reduction of postimplant prostate D90. Methods: A total of 441 patients underwent low‐dose‐rate brachytherapy monotherapy and 474 patients underwent low‐dose‐rate brachytherapy with external beam radiation therapy. Logistic regression analysis was carried out to identify predictive factors for postimplant D90 decline. The cut‐off value of the D90 decline was set at 170 Gy and 130 Gy in the low‐dose‐rate brachytherapy monotherapy group and low‐dose‐rate brachytherapy with external beam radiation therapy group, respectively. Results: On multivariate analysis, neoadjuvant androgen deprivation therapy was identified as an independent predictive factor for the decline of postimplant D90 in both the low‐dose‐rate brachytherapy monotherapy group (P < 0.001) and low‐dose‐rate brachytherapy with external beam radiation therapy group (P = 0.003). Prostate volume changes and computed tomography/transrectal ultrasound prostate volume ratio were significantly and negatively correlated with the postimplant D90. The prostate volume changes and computed tomography/transrectal ultrasound prostate volume ratio were significantly higher in patients with neoadjuvant androgen deprivation therapy than those without neoadjuvant androgen deprivation therapy (P < 0.001). Conclusions: Neoadjuvant androgen deprivation therapy decreased postimplant D90 with substantial prostate gland swelling after low‐dose‐rate brachytherapy. When neoadjuvant androgen deprivation therapy is required to reduce prostate volume for patients with large prostate glands and offer adequate local control for patients with high‐risk prostate cancer before low‐dose‐rate brachytherapy, intraoperative D90 adjustment might be necessary. [ABSTRACT FROM AUTHOR]

Purpose: Low-dose-rate brachytherapy is a key treatment for low-risk or favorable intermediate-risk prostate cancer. The number of radioactive seeds inserted during the procedure depends on prostate volume, and is not easy to predict without pre-planning. Consequently, a large number of unused seeds may be left after treatment. The objective of the present study was to predict the exact number of seeds for future patients using machine learning and a database of 409 treatments. Material and methods: Database consisted of 18 dosimetric and efficiency parameters for each of 409 cases. Nine predictive algorithms based on machine-learning were compared in this database, which was divided into training group (80%) and test group (20%). Ten-fold cross-validation was applied to obtain robust statistics. The best algorithm was then used to build an abacus able to predict number of implanted seeds from expected prostate volume only. As an evaluation, the abacus was also applied on an independent series of 38 consecutive patients. Results: The best coefficients of determination R2 were given by support vector regression, with values attaining 0.928, 0.948, and 0.968 for training set, test set, and whole set, respectively. In terms of predicted seeds in test group, mean square error, median absolute error, mean absolute error, and maximum error were 2.55, 0.92, 1.21, and 7.29, respectively. The use of obtained abacus in 38 additional patients resulted in saving of 493 seeds (393 vs. 886 remaining seeds). Conclusions: Machine-learning-based abacus proposed in this study aims at estimating the necessary number of seeds for future patients according to past experience. This new abacus, based on 409 treatments and successfully tested in 38 new patients, is a good alternative to non-specific recommendations. [ABSTRACT FROM AUTHOR]

Background: Small cell carcinoma of the prostate is a rare condition with important differences from prostatic adenocarcinoma in terms of clinical and prognostic characteristics. A low prostate-specific antigen and a symptomatic patient, including paraneoplastic symptoms, characterize small cell carcinoma of the prostate. Diagnosis is made on the basis of prostate biopsy, and fluorodeoxyglucose positron emission tomography/computed tomography is often used for staging because up to 60% of patients present with de novo metastatic disease. Patients with metastatic disease are usually treated with platinum-based cytotoxic chemotherapy regimens similar to those used for small cell carcinoma of the lung. However, prognosis remains poor, with a median overall survival of 9 to 17 months despite therapy.Case Presentation: This report describes a case of an 80-year-old Caucasian patient with lymph node and bone metastatic small cell carcinoma of the prostate following low-dose-rate brachytherapy for a low-risk prostate carcinoma and treated with chemotherapy and immunotherapy.Conclusion: Low-dose-rate brachytherapy might be an etiology of small cell prostate cancer. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare an isotropic three-dimensional (3D) T2-weighted sequence sampling perfection with application-optimized contrasts by using flip angle evolution (SPACE) with an axial two-dimensional T2-weighted turbo spin echo (TSE) sequence with regard to overall image quality and the delineation of normal prostate and periprostatic anatomy for low-dose-rate prostate cancer brachytherapy planning evaluation. Patients (n = 69) with prostate cancer who had pelvic magnetic resonance imaging (MRI) for low-dose-rate brachytherapy treatment planning were included. Three radiologists independently assessed the visibility of nine anatomic structures on each sequence by using a 5-point scale and overall image quality by using a 4-point scale. The significance of the differences in diagnostic performance was tested with a Wilcoxon signed rank test. No significant intersequence differences were found for most (7/9) anatomical structures and overall image quality. The mean scores for visibility of anatomical structures on the 3D SPACE and 2D TSE sequences, respectively, were as follows: the zonal anatomy (3.7; 3.9, p = 0.05), prostate capsule (3.9; 4.0, p = 0.08), neurovascular bundle (2.9; 2.9, p = 0.9), rectoprostatic angle (3.8; 3.8, p = 0.35), rectum (4.2; 4.3, p = 0.26), urethra (3.8; 3.9, p = 0.12), urinary bladder (4.6; 4.6, p = 0.61), and overall image quality (2.9; 2.9, p = 0.33). 3D SPACE was superior for delineation of the genitourinary diaphragm (3.8; 3.6, p = 0.003), whereas 2D TSE was superior for delineation of the seminal vesicles (3.5; 4.0, p < 0.0001). Anatomic delineation of the prostatic and periprostatic anatomy provided by the 3D SPACE sequence is as robust in quality as that provided by a conventional 2D TSE sequence with superior delineation of the genitourinary diaphragm. For MRI-based brachytherapy treatment planning, the 3D SPACE sequence with subcentimeter isotropic resolution can replace the 2D TSE sequence and be incorporated into standard MRI protocols. [ABSTRACT FROM AUTHOR]

To assess the correlation between postimplant dosimetric quantifiers and the genitourinary (GU) toxicity of low-dose rate brachytherapy for prostate cancer. The minimum urethral dose (UD10, 30, and 90) and the percent volume of the urethra receiving the prescription dose (V100, V150) were calculated from the postimplant dose-volume histograms of 182 patients. We then calculated various urethral biologically equivalent doses (uBEDs) using different values of the α/β ratio and tissue repair half-time (t1/2) and examined the correlations with GU toxicity. Common dosimetric quantifiers, such as UD90 (brachytherapy) + UD50 (external beam radiotherapy), showed no correlation with Grade ≥ 2 GU toxicity. There was a significant correlation between Grade ≥2 GU toxicity and uBED when the α/β value was 0.5 or 1 Gy and t1/2 was 0.5–2.5 h. An uBED (α/β = 1.0, t1/2 = 0.5) had the largest hazard ratio for GU toxicity, and it was also significantly correlated with Grade ≥ 2 GU toxicity according to multivariate analysis. We observed a significant correlation of uBED with GU toxicity when α/β was 0.5 or 1.0 Gy and t1/2 was 0.5–2.5 h. As the simple formula we used has not been verified in basic experiments, more data are needed to validate our results. [ABSTRACT FROM AUTHOR]

Objectives: The aim of the present study was to report on our early experience with hydrogel spacer (SpaceOAR) placement in combination with iodine‐125 low‐dose‐rate brachytherapy for prostate cancer. Methods: From April 2018, SpaceOAR hydrogel spacer was placed in 100 consecutive patients undergoing iodine‐125 low‐dose‐rate brachytherapy. Complications and the status of the placement were evaluated. Deformation of the prostate by the spacer was examined measuring prostate diameters and evaluating the change from preoperative status. The position of the prostate was similarly examined by evaluating the change in distance between the pubic symphysis and the prostate. Post‐plan dosimetric data were compared with 200 patients treated without a spacer. Results: No complications were found during either the intraoperative or perioperative periods. The mean displacement distance of 11.64 mm was created, the mean value before spacer placement was 0.28 mm (P < 0.0001). The change of the prostate diameters showed a positive increase in all directions, with no significant negative change in any one direction. Regarding the change in distance between pubic symphysis and the prostate, no significant shortening trend was observed between the two groups (P = 0.14). Whereas the dosimetric parameters showed means of 0.001 and 0.026 cc for RV150 and RV100 in the spacer group, they were 0.025 and 0.318 cc, respectively, in the non‐spacer group, showing a significant decrease in both parameters (P < 0.001). Conclusions: Prostate deformation secondary to hydrogel placement might adversely affect dosimetric parameters in patients undergoing low‐dose‐rate brachytherapy. However, a significant reduction in the rectal dose can be adopted without adversely affecting the other parameters related to treatment outcome. [ABSTRACT FROM AUTHOR]

Background: The study aimed to compare urinary symptoms in patients with clinically localized prostate cancer after a combination of either low-dose-rate or high-dose-rate interstitial brachytherapy along with intensity-modulated radiation therapy (LDR-ISBT + IMRT or HDR-ISBT + IMRT).Methods: From June 2009 to April 2014, 16 and 22 patients were treated with LDR-ISBT + IMRT and HDR-ISBT + IMRT, respectively. No patient from these groups was excluded from this study. The prescribed dose of LDR-ISBT, HDR-ISBT, and IMRT was 115 Gy, 20 Gy in 2 fractions, and 46 Gy in 23 fractions, respectively. Obstructive and irritative urinary symptoms were assessed by the International Prostate Symptom Score (IPSS) examined before and after treatments. After ISBT, IPSS was evaluated in the 1st and 4th weeks, then every 2-3 months for the 1st year, and every 6 months thereafter.Results: The median follow-up of the patients treated with LDR-ISBT + IMRT and HDR-ISBT + IMRT was 1070.5 days and 1048.5 days, respectively (p = 0.321). The IPSS-increment in the LDR-ISBT + IMRT group was greater than that in the HDR-ISBT + IMRT between 91 and 180 days after ISBT (p = 0.015). In the LDR-ISBT + IMRT group, the IPSS took longer time to return to the initial level than in the HDR-ISBT + IMRT group (in LDR-ISBT + IMRT group, the recovery time was 90 days later). The dose to urethra showed a statistically significant association with the IPSS-increment in the irritative urinary symptoms (p = 0.011). Clinical outcomes were comparable between both the groups.Conclusions: Both therapeutic modalities are safe and well suited for patients with clinically localized prostate cancer; however, it took patients longer to recover from LDR-ISBT + IMRT than from HDR-ISBT + IMRT. It is possible that fast dose delivery induced early symptoms and early recovery, while gradual dose delivery induced late symptoms and late recovery. Urethral dose reductions were associated with small increments in IPSS. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To describe a novel technique that integrates customized sleeved seed production to reduce seed migration using preloaded needles with real-time intraoperative dosimetric planning for patients treated with iodine-125 (I-125) permanent prostate seed implants. Methods and Materials: Customized seed-spacer sequences were calculated for patients in real time based on an intraoperative transrectal ultrasound-guided volume study. Using a Fox Chase Cancer Center modified Best Iodine-125 seed loader (Best Medical, Springfield, VA), the seeds and spacers were inserted into a hollow suture material (sleeve) and then loaded into the implant needles. Needles were placed sequentially under transrectal ultrasound guidance with sagittal plane visualization of the dropped sleeved seeds. Results: This technique was successfully implemented allowing intraoperative planning to be combined with real-time sleeved seed production. Conclusions: The use of sleeves for seeds combined with real-time intraoperative planning allowed for the intraoperative customization of implants with the practical advantages of linked seeds. [Copyright &y& Elsevier]

Purpose: To use the Monte Carlo (MC) method as a dose calculation engine for postimplant dosimetry. To compare the results with clinically approved data for a sample of 28 patients. Two effects not taken into account by the clinical calculation, interseed attenuation and tissue composition, are being specifically investigated. Methods and Materials: An automated MC program was developed. The dose distributions were calculated for the target volume and organs at risk (OAR) for 28 patients. Additional MC techniques were developed to focus specifically on the interseed attenuation and tissue effects. Results: For the clinical target volume (CTV) D(90) parameter, the mean difference between the clinical technique and the complete MC method is 10.7 Gy, with cases reaching up to 17 Gy. For all cases, the clinical technique overestimates the deposited dose in the CTV. This overestimation is mainly from a combination of two effects: the interseed attenuation (average, 6.8 Gy) and tissue composition (average, 4.1 Gy). The deposited dose in the OARs is also overestimated in the clinical calculation. Conclusions: The clinical technique systematically overestimates the deposited dose in the prostate and in the OARs. To reduce this systematic inaccuracy, the MC method should be considered in establishing a new standard for clinical postimplant dosimetry and dose-outcome studies in a near future. [ABSTRACT FROM AUTHOR]