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PURPOSE To evaluate the PSA outcomes and the late patient's reported health related quality of life (HRQOL) and toxicity after single-fraction High-Dose-Rate brachytherapy (HDRB) and Low-Dose-Rate brachytherapy (LDRB) for prostate cancer. METHODS Men with low and favorable intermediate-risk prostate cancer across 3 centres were randomized between monotherapy brachytherapy with either Iodine-125 LDRB or 19 Gy single-fraction HDRB. Biochemical outcomes were evaluated using the Phoenix definition, PSA nadir and absolute PSA value

Vertebral compression fractures (VCF) are a common and severe complication of spine stereotactic body radiation therapy (SBRT). We sought to analyze how volumetric dosimetry and clinical factors were associated with the risk of VCF.We evaluated 173 spinal segments that underwent single fraction SBRT in 85 patients from a retrospective database. Vertebral bodies were contoured and dosimetric values were calculated. Competing risk models were used to evaluate the effect of clinical and dosimetry variables on the risk of VCF.Our primary endpoint was development of a post-SBRT VCF. New or progressive fractures were noted in 21/173 vertebrae (12.1%); the median time to fracture was 322 days. Median follow-up time was 426 days. Upon multivariable analysis, the percentages of vertebral body volume receiving20 Gy and24 Gy were significantly associated with increased risk of VCF (hazard ratio, 1.036, 1.104; P = .029, .044, respectively). No other patient or treatment factors were found to be significant on multivariable analysis. Sensitivity analysis revealed that the percentages of vertebral body volume receiving20 Gy and24 Gy required to obtain 90% sensitivity for predicting vertebral body fracture were 24% and 0%, respectively.VCF is a common complication after SBRT, with a crude incidence of 12.1%. Treatment plans that permit higher volumes receiving doses20 Gy and24 Gy to the vertebral body are associated with increased risk of VCF. To achieve 90% sensitivity for predicting VCF post-SBRT, the percentage of vertebral volume receiving20 Gy should be24% and maximum point dose should be24 Gy. These results may help guide clinicians when evaluating spine SBRT treatment plans to minimize the risk of developing posttreatment VCF.

Purpose To clarify the role of stereotactic radiosurgery (SRS) for atypical meningiomas (AM). Methods A retrospective analysis of 68 patients with AM having SRS from 1995 until 2019. Results Nineteen patients (28%) had undergone prior external beam radiation therapy (EBRT) (median dose, 54 Gy). The median follow-up period was 52 months. Eighteen (26%), 17 (25%), and 33 (49%) patients received SRS as an upfront adjuvant (≤ 6 months), early salvage (7-18 months), or late salvage treatment (> 18 months), respectively. The 3-, 5-, and 10-year progression-free survivals (PFSs) were 52%, 35%, and 25%, respectively. The 3-, 5-, and 10-year disease-specific survivals were 85%, 78%, and 61%, respectively. Adverse radiation events (AREs) were observed in 12 patients (18%), with increased or new seizures being the most frequent complication (n = 7). Prior EBRT was associated with reduced PFS (HR 5.92, P Conclusion PFS for patients with residual/recurrent AM remains poor despite SRS. Prior EBRT was associated with worse tumor control, higher tumor-related mortality, and an increased risk of ARE. Further study on the timing of SRS is needed to determine if upfront adjunctive SRS improves tumor control compared to salvage SRS.

Accelerated partial breast irradiation (APBI) represents a validated technique for low-risk breast cancer. Recently, ultra-APBI (uAPBI) using fewer than 5 fractions was described in the literature. We compared clinical outcomes and late toxicity after APBI or uAPBI in older patients.Two cohorts of older patients (aged ≥70 years) with low-risk breast cancer treated with APBI (interstitial brachytherapy) were analyzed retrospectively. A total dose of 34 Gy in10 fractions (APBI) or 16 Gy in 1 fraction (uAPBI) was delivered from 2004 to 2012 and from 2013 to 2018, respectively. Oncologic outcome analyzed the cumulative incidence of local relapse, regional relapse, and distant metastases with disease-free survival, cause-specific survival, and overall survival. Late toxicity and cosmetic results were investigated.One hundred fifty-seven patients (APBI, n = 109 patients; uAPBI, n = 48 patients) underwent APBI according to the same selection criteria. Apart from the median follow-up (97 vs 72 months for APBI and uAPBI; P.002), no significant difference was noted between the 2 groups. Regarding 6-year oncologic outcome, no significant difference was observed between APBI and uAPBI for local recurrence (1.3% vs 0%; P = .4), regional recurrence (2.5% vs 2.3%; P = .9), distant metastases (4.3% vs. 2.4%; P = .6), disease-free survival (85.2% vs. 82.2%; P = .8), cause-specific survival (96.7% vs. 96.2%; P = .9), and overall survival (86.7% vs. 82.2%; P = .7). Regarding late toxicity, no significant difference was observed between APBI and uAPBI (total complication number, 45 vs 33%; P = .173) with only grade 1 (88.4% vs. 95%) and grade 2 (11.6% vs. 5%) late toxicities (P = .677). Similarly, no significant difference was observed for excellent/good cosmetic results between the 2 cohorts (P = .98).We report the first study comparing APBI versus uAPBI in a cohort of older patients with low-risk breast cancer. No significant difference was found between the 2 treatment groups regarding oncologic outcome, late toxicity, and cosmetic result. uAPBI based on a single fraction of brachytherapy represents an attractive option for therapeutic de-escalation in older patients with breast cancer.

BACKGROUND/AIM The aim of this study was to identify prognostic factors for brain metastases treated with Gamma knife radiosurgery. PATIENTS AND METHODS Multivariate Cox proportional hazards regression analyses were conducted for patients who received treatment between June 2013 and March 2018. RESULTS A total of 131 consecutive patients were included. The median follow-up period was 16.0 months (range=1.5-61.5 months). Brain metastases [hazard ratio (HR)=0.42, 95%CI=0.27-0.67, p

We aimed to evaluate the impact of rotational setup errors on the doses received during postoperative volumetric-modulated arc therapy (VMAT) for cervical cancer. Overall, 121 cone-beam computed tomography (CBCT) sets from 20 patients were rigidly registered to reference computed tomography (CT) sets based on bony landmarks. The rotational setup errors (pitch, yaw and roll) were calculated. Then, 121 CT sets involving rotational setup errors were created, and the dose distribution in these CT sets were recalculated. The recalculated dosimetric parameters for the clinical target volume (CTV) and organs at risk (OAR) were compared to the reference values, and the correlation coefficients between the dosimetric parameter differences and rotational setup errors were calculated. Only the pitch setup error was moderately correlated with CTV coverage (r ≥ 0.40) and strongly correlated with V45 for the bladder (r ≥ 0.91) and V40 for the rectum, small bowel and bone marrow (r ≥ 0.91). The maximum dosimetric difference in a single fraction and overall fractions was −1.59% and −0.69% in D98 for the CTV, 11.72% and 5.17% in V45 for the bladder and −8.03% and −4.68% in V40 for the rectum, respectively. In conclusion, rotational setup errors only slightly impact dose coverage during postoperative cervical cancer VMAT. However, the pitch setup error occasionally affected the doses received by the bladder or the rectum in the overall fraction when the error was systematic. Thus, rotational setup errors should be corrected by adjusting six-degree-of-freedom (DOF) couches to reduce dosimetric differences in the OARs.

Highlights • 165 new brain lesions in 38 patients who had prior SRS for brain metastases. • 73% primary lung cancer patients. • Lower incidence of new lesions with increasing dose received by the region from prior SRS. • Accounting for discrepancies in both volume of the brain and follow-up period, regions that received doses of 4 Gy or more from previous SRS had 3 or fewer new lesions compared to 17 new lesions per 100 cm3 brain per year in regions that received 1 Gy or less., Purpose/Objective(s) Stereotactic radiosurgery (SRS) for metastatic disease to the brain is associated with higher in-brain failures compared to whole brain radiation therapy (WBRT). Here we investigated the relationship between low-dose fall off during SRS and location of new brain lesions. Materials and Methods One hundred sixty-seven patients treated with single fraction or fractionated SRS for intact or resected brain metastases at our institution from January 2016 to June 2018 were reviewed. Patients with imaging findings of new brain metastases after the initial SRS were included. Patients with WBRT before SRS were excluded. MRI scans for repeat treatments were fused with initial SRS plan. New lesions were outlined on the initial SRS planning CT. The mean dose that the site of new lesions received from initial SRS was tabulated. Results Thirty-eight patients met inclusion criteria. 165 new lesions were evaluated. There was a lower propensity to develop new brain lesions with increasing dose received by the regions from prior SRS, with 66%, 34%, 19%, 13%, 6%, 5%, 2% and 1% of new lesions appearing in regions that received less than 1 Gy, greater than or equal to 1, 2, 3, 4, 5, 6, and 7 Gy, respectively. Higher doses are received by smaller brain volumes during SRS. After accounting for volume, 14, 14, 11, 7, 2, 2, 1 and 1 new lesions appeared per 100 cm3 of brain in regions that received doses of less than 1 Gy, greater than or equal to 1, 2, 3, 4, 5, 6, and 7 Gy, respectively, from prior SRS. Conclusions We identified low dose spillage during SRS to be associated with lower incidence of new brain metastases. Validation in larger dataset or prospective study of the combination of SRS with low dose WBRT would be crucial in order to establish causality of these findings.

We report long-term outcomes from our phase 1 dose-escalation study to determine the maximum tolerated dose of single-fraction liver SABR pooled with our subsequent single institutional experience with patients treated postprotocol at the highest dose level (40 Gy) established from the phase 1 study.Patients with liver metastases from solid tumors located outside of the central liver zone were treated with single-fraction SABR on a phase 1 dose escalation trial. At least 700 cc of normal liver had to receive9.1 Gy. Seven patients with 10 liver metastases received the initial prescription dose of 35 Gy, and dose was then escalated to 40 Gy for 7 more patients with 7 liver metastases. An additional 19 postprotocol patients with 22 liver metastases were treated to 40 Gy in a single fraction. Patients were followed for toxicity and underwent serial imaging to assess local control.Median imaging follow-up for the combined cohort (n = 33, 39 lesions) was 25.9 months; 38.9 months for protocol patients and 20.2 months for postprotocol patients. Median lesion size was 2.0 cm (range, 0.5-5.0 cm). There were no dose-limiting toxicities observed for protocol patients, and only 3 grade 2 toxicities were observed in the entire cohort, with no grade ≥3 toxicities attributable to treatment. Four-year actuarial local control of irradiated lesions in the entire cohort was 96.6%, 100% in the protocol group and 92.9% in the subsequent patients. Two-year overall survival for all treated patients was 82.0%.For selected patients with liver metastases, single-fraction SABR at doses of 35 and 40 Gy was safe and well-tolerated, and shows excellent local control with long-term follow-up; results in subsequent patients treated with single-fraction SABR doses of 40 Gy confirmed our earlier results.

Purpose: To reconstruct the dose delivered during single-fraction urethra-sparing prostate stereotactic body radiotherapy (SBRT) accounting for intrafraction motion monitored by intraprostatic electromagnetic transponders (EMT). Methods: We analyzed data of 15 patients included in the phase I/II "ONE SHOT" trial and treated with a single fraction of 19 Gy to the planning target volume (PTV) and 17 Gy to the urethra planning risk volume. During delivery, prostate motion was tracked with implanted EMT. SBRT was interrupted when a 3-mm threshold was trespassed and corrected unless the offset was transient. Motion-encoded reconstructed (MER) plans were obtained by splitting the original plans into multiple sub-beams with isocenter shifts based on recorded EMT positions, mimicking prostate motion during treatment. We analyzed intrafraction motion and compared MER to planned doses. Results: The median EMT motion range (±SD) during delivery was 0.26 ± 0.09, 0.22 ± 0.14 and 0.18 ± 0.10 cm in the antero-posterior, supero-inferior, and left-right axes, respectively. Treatment interruptions were needed for 8 patients because of target motion beyond limits in the antero-posterior (n = 6) and/or supero-inferior directions (n = 4). Comparing MER vs. original plan there was a median relative dose difference of -1.9% (range, -7.9 to -1.0%) and of +0.5% (-0.3-1.7%) for PTV D98% and D2%, respectively. The clinical target volume remained sufficiently covered with a median D98% difference of -0.3% (-1.6-0.5%). Bladder and rectum dosimetric parameters showed significant differences between original and MER plans, but mostly remained within acceptable limits. Conclusions: The dosimetric impact of intrafraction prostate motion was minimal for target coverage for single-fraction prostate SBRT with real-time electromagnetic tracking combined with beam gating. Keywords: Dose reconstruction; Electromagnetic transponder; Intrafraction motion; Prostate cancer; Single-fraction; Stereotactic body radiotherapy.

Background Limited brain metastasis is treated definitively with stereotactic radiosurgery when surgical resection is not indicated. Although this has historically been performed in a single fraction, multi-fraction approaches such as fraction radiosurgery (FSRS) and staged radiosurgery (SSRS) have been recently examined as alternative approaches for larger lesions to permit better tumor control without increased toxicity. Case report We present the case of a patient who developed symptomatic radionecrosis in two brain metastasis, 2.3 cm and 2.1 cm in size, which were treated with 18 Gy in one fraction, but no radionecrosis in a 3.3 cm lesion treated in two fractions of 15 Gy nor in two punctate lesions that were treated in one fraction of 20 Gy. Although she did not respond to steroids, she responded to bevacizumab symptomatically and on neuroimaging. Conclusion Congruent with other recent studies, our report suggests that large brain metastasis should be considered for FSRS/SSRS.

External Beam Radiotherapy (EBRT) allows remarkable pain control in patients with skeletal metastases. We performed a Bayesian network meta-analysis comparing the most commonly used radiotherapy regimens for palliative management in patients with skeletal metastases. The main online databases were accessed in October 2020. All randomized clinical trials evaluating the irradiation of painful bone metastases were considered. The following irradiation patterns were analysed and included in the present network meta-analysis: 8 Gy- and 10 Gy/single fraction, 20 Gy/5 fractions, 30 Gy/10 fractions. The Bayesian hierarchical random-effect model analysis was adopted in all comparisons. The Log Odds-Ratio (LOR) statistical method for dichotomic data was adopted for analysis. Data from 3595 patients were analysed. The mean follow-up was 9.5 (1 to 28) months. The cumulative mean age was 63.3 ± 2.9. 40.61% (1461 of 3595 patients) were female. The 8Gy/single fraction protocol detected reduced rate of “no pain response” (LOR 3.39), greater rate of “pain response” (LOR-5.88) and complete pain remission (LOR-7.05) compared to the other dose patterns. The 8Gy group detected a lower rate of pathological fractures (LOR 1.16), spinal cord compression (LOR 1.31) and re-irradiation (LOR 2.97) compared to the other dose patterns. Palliative 8Gy/single fraction radiotherapy for skeletal metastases shows outstanding results in terms of pain control, re-irradiations, pathological fractures and spinal cord compression, with no differences in terms of survivorship compared to the other multiple dose patterns.Level of evidence: I, Bayesian network meta-analysis of RCTs.

OBJECTIVEStereotactic body radiation therapy (SBRT) offers efficient, noninvasive treatment of spinal neoplasms. Single-fraction (SF) high-dose SBRT has a relatively narrow therapeutic window, while hypofractionated delivery of SBRT may have an improved safety profile with similar efficacy. Because the optimal approach of delivery is unknown, the authors examined whether hypofractionated SBRT improves pain and/or functional outcomes and results in better tumor control compared with SF-SBRT.METHODSThis is a single-institution retrospective study of adult patients with spinal metastases treated with SF- or three-fraction (3F) SBRT from 2008 to 2019. Demographics and baseline characteristics, radiographic data, and posttreatment outcomes at a minimum follow-up of 3 months are reported.RESULTSOf the 156 patients included in the study, 70 (44.9%) underwent SF-SBRT (median total dose 1700 cGy) and 86 (55.1%) underwent 3F-SBRT (median total dose 2100 cGy). At baseline, a higher proportion of patients in the 3F-SBRT group had a worse baseline profile, including severity of pain (p < 0.05), average use of pain medication (p < 0.001), and functional scores (p < 0.05) compared with the SF-SBRT cohort. At the 3-month follow-up, the 3F-SBRT cohort experienced a greater frequency of improvement in pain compared with the SF-SBRT group (p < 0.05). Furthermore, patients treated with 3F-SBRT demonstrated a higher frequency of improved Karnofsky Performance Scale (KPS) scores (p < 0.05) compared with those treated with SF-SBRT, with no significant difference in the frequency of improvement in modified Rankin Scale scores. Local tumor control did not differ significantly between the two cohorts.CONCLUSIONSPatients who received spinal 3F-SBRT more frequently achieved significant pain relief and an increased frequency of improvement in KPS compared with those treated with SF-SBRT. Local tumor control was similar in the two groups. Future work is needed to establish the relationship between fractionation schedule and clinical outcomes.

PURPOSE: Stereotactic body radiation therapy (SBRT) for early stage non-small cell lung cancer (NSCLC) is a standard of care for medically inoperable patients. Our aim was to compare Common Terminology Criteria for Adverse Events (CTCAE) thoracic grade 3 or higher adverse events (AEs) of 30 Gy in one fraction (arm 1) vs. 60 Gy in 3 fractions (arm 2). METHODS: This was a randomized multi-institutional, phase II, two-arm, clinical trial. Medically inoperable patients with biopsy-proven peripheral T1/T2N0M0 NSCLC tumors were enrolled. Patients were randomized to arm 1 or arm 2 and stratified by performance status. The primary endpoint was CTCAE thoracic grade 3 or higher AEs. Secondary end points were local control (LC), progression-free survival (PFS), overall survival (OS), and quality of life (QOL). RESULTS: Between September, 2008 and April, 2015, 98 patients were randomized. Median follow-up was 53.8 months. 10 patients were lost to follow-up; 1 in arm 1 and 9 in arm 2. Thoracic grade 3 AEs were experienced by 8 (16%) patients on arm 1 and 6 (12%) patients on arm 2 there were no grade 4 or 5 AEs.. There were no differences in LC, PFS or OS (p= 0.68, 0.86 and 0.94, respectively). Arm 1 reported better social functioning (p=0.006) with less dyspnea (p=0.016) in follow-up at 6 months. CONCLUSIONS: This randomized phase II study demonstrated 30 Gy in one fraction was equivalent to 60 Gy in three fractions in terms of toxicity, LC, PFS and OS. QOL measures of social functioning and dyspnea favored single fraction SBRT.

Purpose At our department, MR-guided stereotactic body radiation therapy (SBRT) using the 1.5T MR-linac system (Unity, Elekta AB, Stockholm, Sweden) has been initiated for patients with lymph node oligometastases. Superior soft tissue contrast and the possibility for online plan adaptation on the Unity may allow for hypofractionated treatment. The purpose of this study was to investigate the dosimetric feasibility and compare the plan quality of different hypofractionated schemes. Methods and materials Data was used from 12 patients with single lymph node oligometastases (10 pelvic, 2 para-aortic), which were all treated on the Unity with a prescribed dose of 5x7 Gy to 95% of the PTV. Hypofractionation was investigated for 3x10 Gy and 1x20 Gy schemes (all 60 Gy BED α/β = 10). The pre-treatment plans were evaluated based on dose criteria and plan quality. If all criteria were met, the number of online adapted plans which also met all dose criteria was investigated. For pre-treatment plans meeting the criteria for all three fractionation schemes, the plan quality after online adaptation was compared using the four parameters described in the NRG-BR001 phase 1 trial. Results Pre-treatment plans met all clinical criteria for the three different fractionation schemes in 10, 9 and 6 cases. 50/50, 45/45 17/30 of the corresponding online adapted plans met all criteria, respectively. Violations were primarily caused by surrounding organs at risk overlapping or adjacent to the PTV. The 1x20 Gy treatment plans were, in general, of lesser quality than the 5x7 Gy and 3x10 Gy plans. Conclusion Hypofractionated radiotherapy for lymph node oligometastases on the 1.5T MR-linac is feasible based on dose criteria and plan quality metrics. The location of the target relative to critical structures should be considered in choosing the most suitable fractionation scheme. Especially for single fraction treatment, meeting all dose criteria in the pre-treatment situation does not guarantee that this also applies during online treatment.

Purpose Conventionally fractionated, post-operative radiotherapy (cPORT; 50 Gy in 25 fractions) is considered for patients with Merkel cell carcinoma (MCC) to improve locoregional control. However, cPORT is associated with acute toxicity, especially in the head and neck (H&N) region, and requires daily treatments over several weeks. We previously reported high rates of durable local control with minimal toxicity using 8 Gy single-fraction radiation therapy (SFRT) in the metastatic setting. We report early results on a cohort of patients with localized H&N MCC, who received post operative SFRT if a cPORT regimen was not feasible. Methods Twelve patients with localized MCC of the H&N (clinical/pathologic stages: I-II) and no prior RT to the region were identified from an IRB-approved prospective registry who underwent surgical resection followed by post operative SFRT. Time-to-event was calculated starting from the date of resection prior to SFRT. The cumulative incidence of in-field locoregional recurrences and out-of-field recurrences was estimated with death as a competing risk. Results Twelve H&N MCC patients were identified with clinical/pathologic stages I-II H&N MCC. Median age at diagnosis was 81 years (58-96); 25% had immunosuppression. At a median follow-up of 19 months (range: 8-34), there were no in-field locoregional recurrences. A single out-of-field regional recurrence was observed, which was successfully salvaged. There were no MCC specific-deaths. No radiation-associated toxicities greater than grade 1 (CTCAE v5) were observed. Conclusions Preliminary data suggest that SFRT could offer a potential alternative to cPORT to treat the primary site for localized H&N MCC, particularly in elderly or frail patients, with promising in-field local control and minimal toxicity. Further data with validation in larger cohorts is needed to confirm the sustained safety and efficacy of post operative SFRT., Merkel cell carcinoma (MCC) is often treated with excision followed by conventional fractionated radiotherapy for localized disease. Single fraction radiation therapy (SFRT) has been shown to be effective for treating patients with metastatic MCC. This study presents early results for patients with MCC of the head and neck treated with 8 Gy SFRT to the post operative bed following surgery.

Spine stereotactic radiosurgery (SSRS) offers high rates of local control in a critical anatomic area by delivering precise, ablative doses of radiation for treatment of spine metastases. However, the dose tolerance of the spinal cord (SC) after SSRS with relation to radiation myelopathy (RM) is not well-described.We reviewed patients who underwent single fraction, de novo SSRS from 2012-2017 and received12 Gy Dmax to the SC, defined using MRI-CT fusion without PRV expansion. The standard SC constraint was D0.01cc ≤ 12 Gy. Local control was estimated with the Kaplan-Meier method. Bayesian analysis was used to compute posterior probabilities for RM.A total of 146 SSRS treatments among 132 patients were included. The median SC Dmax was 12.6 Gy (range, 12.1-17.1 Gy). The SC Dmax was12 and13 Gy for 109 (75%) treatments, ≥13 and14 Gy for 28 (19%) treatments, and ≥14 Gy for 9 (6%) treatments. The 1-year local control rate was 94%. With a median follow-up time of 42 months, there were zero (0) RM events observed. Assuming a prior 4.3% risk of RM, the true rate of RM for SC Dmax of ≤14 Gy was computed as1% with 98% probability.In one of the largest series of patients treated with single fraction, de novo SSRS, there were no cases of RM observed with a median follow-up of 42 months. These data support safe relaxation of MRI-defined SC dose up to D0.01cc ≤ 12 Gy, which corresponds to1% risk of RM.

We review a case of inoperable early stage breast cancer treated definitively with the use of stereotactic ablative radiotherapy (SABR). A 57-year-old female with a history of decompensated cirrhosis with early stage breast cancer was treated with 25 Gy in one fraction. At her 7-month follow up visit, there was a complete resolution of disease on imaging. This case represents a novel approach for the treatment of breast cancer with SABR when surgery is contraindicated.

To assess the therapeutic potential of single-fraction robotic stereotactic ablative body radiotherapy (SABR) in patients with locally recurrent prostate cancer (PC) after radical prostatectomy (RP).We included 35 patients with biochemical failure after RP with single-site local recurrence in the prostate bed diagnosed by PSMA PET/CT. About 20/35 pts had previously received post-surgical adjuvant radiation therapy.High-resolution multiparametric magnetic resonance imaging (mpMRI) for exact visualization of tumor tissue was performed at 1.5 (n = 23; Siemens Magnetom Aera) or 3 Tesla (n = 12; Siemens Magnetom VIDA, Siemens Healthineers, Erlangen, Germany). Using the MRI and PET/CT dataset for planning, SABR was carried out after ultrasound-guided placement of a single gold fiducial marker at the site of tumor recurrence using a CyberKnife M6 unit (Accuray Inc., Sunnyvale, USA). Due to the high diagnostic accuracy of PSMA PET/CT and mpMRI, pre-SABR biopsy of tumor tissue was not deemed necessary. PSMA PET/CT performed in median 88 days before SABR confirmed the absence of distant metastases. MpMRI was performed at a median of 22 days prior to the intervention. SABR was performed in a single fraction with a dose of 20 (5/35), 21 (27/35) or 22 (3/35) Gy. Follow-up serum PSA was measured every 3 months thereafter.Median patient age was 72 years (57-80 years) and median time from RP to SABR was 96.8 months (IQR, 69.3-160.2). Median serum PSA before SABR was 1.38 ng/mL (IQR 0.75-2.72). At 3 months, median PSA had dropped significantly in 27/35 patients to a median of 0.35 ng/mL (IQR 0.25-0.68). At 6 months, 30/35 patients showed biochemical response to SABR, while five patients were progressing: three had systemic disease on PSMA PET/CT, while two patients had rising PSA values without a visible correlate on PET/CT. The median follow-up time was 16 months. Grade 1 genitourinary (GU) toxicity was reported in 3/35 patients (9%) and grade 1 gastrointestinal (GI) toxicity in 2/35 patients (6%), respectively.SABR is an efficient new treatment option in the management of single-site local recurrent PC without the evidence of systemic disease; due to its very low toxicity, it is an alternative to surgical re-treatment or other focal therapies. It can significantly delay the onset of androgen deprivation therapy (ADT) in biochemical failure after radical prostatectomy.

Highlights • SBRT may provide a non-invasive treatment option for recurrent prostate cancer. • MR-Linac single fraction 19 Gy treatment of recurrent prostate cancer is feasible. • MR-Linac dose distributions for the target were comparable to HDR-brachytherapy. • Real-time intrafraction adaptation techniques are needed for clinical introduction., Background and Purpose Magnetic resonance imaging (MRI)-guided focal salvage high-dose-rate brachytherapy (FS-HDR-BT) is one of the treatment options for radiorecurrent localized prostate cancer. However, due to the invasive nature of the treatment, not all patients are eligible. Magnetic resonance linear accelerator (MR-Linac) systems open up new treatment possibilities and could potentially replace FS-HDR-BT treatment. We conducted a planning study to investigate the feasibility of delivering a single 19 Gy dose to the recurrent lesion using a 1.5 Tesla MR-Linac system. Materials and Methods Thirty patients who underwent FS-HDR-BT were included. The clinical target volume (CTV) encompassed the visible lesion plus a 5 mm margin. Treatment plans were created for a 1.5 Tesla MR-Linac system using a 1 mm planning target volume (PTV) margin. A dose of 19 Gy was prescribed to ≥ 95% of the PTV. In case this target could not be reached, i.e. when organs-at-risk (OAR) constraints were violated, a dose of ≥ 17 Gy to ≥ 90% of the PTV was accepted. MR-Linac plans were compared to clinical FS-HDR-BT plans. Results Target dose coverage was achieved in 14/30 (47%) FS-HDR-BT plans and 17/30 (57%) MR-Linac plans, with comparable median D95% and D90%. In FS-HDR-BT plans, a larger volume reached ≥ 150% of the prescribed dose. Urethra D10%, rectum D1cm3, and rectum D2cm3 were lower in the FS-HDR-BT plans, while bladder dose was comparable for both modalities. Conclusion Single fraction treatment of recurrent prostate cancer lesions may be feasible using stereotactic body radiotherapy (SBRT) on a MR-Linac system.

The Gamma Knife ® planning software (TMR 10, Elekta Instruments, AB, Sweden) affords two ways of defining the skull volume, the "historical" one using manual measurements (still perform in some centers) and the new one using image-based skull contours. Our objective was to assess the potential variation of the dose delivery calculation using consecutively in the same patients the two above-mentioned techniques. We included in this self-case-control study, 50 patients, treated with GKRS between July 2016 and January 2017 in Lausanne University Hospital, Switzerland, distributed among four groups: convexity targets (n = 18), deep-seated targets (n = 13), vestibular schwannomas (n = 11), and trigeminal neuralgias (n = 8). Each planning was performed consecutively with the 2 skull definition techniques. For each treatment, we recorded the beam-on time (min), target volume coverage (%), prescription isodose volume (cm 3 ), and maximal dose (Gy) to the nearest organ at risk if relevant, according to each of the 2 skull definition techniques. The image-based contours were performed using CT scan segmentation, based upon a standardized windowing for all patients. The median difference in beam-on time between manual measures and image-based contouring was + 0.45 min (IQR; 0.2-0.6) and was statistically significant (p < 0.0001), corresponding to an increase of 1.28% beam-on time per treatment, when using image-based contouring. The target location was not associated with beam-on time variation (p = 0.15). Regarding target volume coverage (p = 0.13), prescription isodose volume (p = 0.2), and maximal dose to organs at risk (p = 0.85), no statistical difference was reported between the two skull contour definition techniques. The beam-on time significantly increased using image-based contouring, resulting in an increase of the total dose delivery per treatment with the new TMR 10 algorithm. Other dosimetric parameters did not differ significantly. This raises the question of other potential impacts. One is potential dose modulation that should be performed as an adjustment to new techniques developments. The second is how this changes the biologically equivalent dose per case, as related to an increased beam on time, delivered dose, etc., and how this potentially changes the radiobiological effects of GKRS in an individual patient.

Vestibular schwannoma (VS), also referred to as acoustic neuroma, is one of the common benign intracranial tumors with rising incidence due to improved and more frequent neuroimaging.

PURPOSE To evaluate three different formulae for calculating the biologically effective dose (BED) by use of a multipopulation reaction-diffusion simulation to determine whether these formulae produce equivalent effects for different treatment regimes. METHODS The standard BED formula, BEDs , was updated to account both for spacial nonuniformity in dose and for cellular regrowth between fractions, by creating two new formulae: BEDϕ and BEDϕT . These BED formulae were used to calculate dose per fraction values for two, three, and five fraction treatments and to compare the tumor volumes of those treatments to those of a single fraction. A spherical tumor model based on the reaction-diffusion equation was used to calculate the final volume of each tumor 185 days after the delivery of the first fraction. The percent difference in volume between single-fraction and multiple-fraction treatments was used as a measure to test the accuracy of each BED formula. RESULTS Percent differences in volume between single- and multiple-fraction treatment regimes varied up to approximately 18.5% if the dose per fraction was calculated using BEDs but the delivered dose was nonuniform. Proper application of spacial nonuniformity in dose and tumor regrowth correction factors modified the dose per fraction values by no more than 5%, but resulted in the improvement of simulated tumor volumes down to around 2% or lower difference in volume. CONCLUSIONS Treatment regimes with the same BED value should have the same effect. However, small changes in the dose per fraction delivered in multiple-fraction treatments can have a large effect on the tumor volume of a treatment when the dose is delivered nonuniformly or when tumor regrowth between fractions is ignored. Inclusion of these correction factors is important for the underlying assumption that treatments with equal BED will have equal effects on the clinically observed tumor volume.

Standard treatment for early-stage invasive breast cancer (bca) consists of breast-conserving surgery and several weeks of adjuvant radiotherapy (rt). Neoadjuvant single-fraction rt is a novel approach for early-stage bca. We sought to investigate the effect of delaying surgery after neoadjuvant rt with respect to the rate of pathologic response (pr). Women 65 years of age or older with a new diagnosis of stage i luminal A bca were eligible for inclusion. A single 20 Gy dose to the primary breast tumour was given, followed by breast-conserving surgery 3 months later. The primary endpoint was the pr rate assessed by microscopic evaluation using the Miller&ndash, Payne system. To date, 10 patients have been successfully treated. Median age of the patients was 72 years (range: 65&ndash, 84 years). In 8 patients, neoadjuvant rt resulted in a tumour pr with median residual cellularity of 3%. No immediate rt complications other than mild dermatitis were noted. This study demonstrates a method for delivering single-fraction rt that can lead to a high level of pr in most patients. Continued accrual to this study and subsequent trials are needed to determine the feasibility, safety, and role of this novel technique in the management of early-stage bca.

BACKGROUND/AIM Seizures represent a major problem for patients with brain metastases. This study evaluated the role of seizures in patients receiving single-fraction radiosurgery (SRS) or multi-fraction stereotactic radiotherapy (FSRT). PATIENTS AND METHODS This retrospective study included 195 patients receiving SRS (n=164) or FSRT (n=31) alone for one to three brain metastases. The prevalence of pre-SRS/FSRT seizures and correlations with pre-treatment factors were investigated. These factors plus pre-SRS/FSRT seizures were assessed in regard to survival. RESULTS Thirty-three patients had pre-SRS/FSRT seizures (prevalence=16.9%). Seizures were significantly correlated with age ≤61 years. Trends were observed for seizures being more frequent in those with NSCLC and those without extra-cranial metastatic spread. On multivariate analysis, significant associations with improved survival were found for Karnofsky performance score ≥80%, breast cancer, and an interval from diagnosis of malignant disease to SRS/FSRT ≥21 months. CONCLUSION Younger age, NSCLC and absence of extra-cranial spread appeared to be risk factors for seizures prior to SRS/FSRT. Having seizures prior to SRS/FSRT showed no association with survival.

Peripheral lung lesions treated with a single fraction of stereotactic ablative body radiotherapy (SABR) utilizing volumetric modulated arc therapy (VMAT) delivery and flattening filter‐free (FFF) beams represent a potentially high‐risk scenario for clinically significant dose blurring effects due to interplay between the respiratory motion of the lesion and dynamic multi‐leaf collimators (MLCs). The aim of this study was to determine an efficient means of developing low‐modulation VMAT plans in the Eclipse treatment planning system (v15.5, Varian Medical Systems, Palo Alto, USA) in order to minimize this risk, while maintaining dosimetric quality. The study involved 19 patients where an internal target volume (ITV) was contoured to encompass the entire range of tumor motion, and a planning target volume (PTV) created using a 5‐mm isotropic expansion of this contour. Each patient had seven plan variations created, with each rescaled to achieve the clinical planning goal for PTV coverage. All plan variations used the same field arrangement, and consisted of one dynamic conformal arc therapy (DCAT) plan, and six VMAT plans with varying degrees of modulation restriction, achieved through utilizing different combinations of the aperture shape controller (ASC) in the calculation parameters, and monitor unit (MU) objective during optimization. The dosimetric quality was assessed based on RTOG conformity indices (CI100/CI50), as well as adherence to dose–volume metrics used clinically at our institution. Plan complexity was assessed based on the modulation factor (MU/cGy) and the field edge metric. While VMAT plans with the least modulation restriction achieved the best dosimetry, it was found that there was no clinically significant trade‐off in terms of dose to organs at risk and conformity by reducing complexity. Furthermore, it was found that utilizing the ASC and MU objective could reduce plan complexity to near‐DCAT levels with improved dosimetry, which may be sufficiently robust to overcome the interplay effect.

Aim:To investigate whether a radiographer-led radiotherapy pathway can provide an efficient service for patients requiring treatment for symptomatic skeletal metastases.Materials and Methods:A retrospective review of 425 courses of palliative radiotherapy was conducted. Data was analysed assessing diagnosis, dose/fractionation, time from referral to treatment, gender, age, inpatient/outpatient status and referring clinic location for radiographer- and clinical oncologist-led cohorts.Results:Patients aged ≥70 years were more likely to be planned by radiographers (n = 162/57, p n = 279/136, p = 0·012). The median referral to treatment time in 8-Gy single-fraction prescriptions was 3 days for radiographer-led versus 7 days for clinical oncologist-led cohorts. In all patients and in 20 Gy in five-fraction prescriptions, it was 4 versus 8 days. A comparison of all prescriptions (p p p = 0·001) showed radiographer-led procedures as enabling faster access to treatment in each category.Findings:A radiographer-led service can facilitate faster access to treatment than a clinical oncologist-led pathway for an appropriately selected patient caseload.

When treating solid tumor spine metastases, stereotactic high-dose-per-fraction radiation, given in a single fraction or in a hypofractionated approach, has proved to be a highly effective and safe therapeutic option for any tumor histology, in the setting of de novo therapy, as salvage treatment of local progression after previous radiation, and in the postoperative setting. There are variations in practice based on the clinical presentation, goals of therapy, as well as institutional preferences. As a biologically potent therapy, a thoughtful and careful attention to detail with patient selection, treatment planning, and delivery is crucial for treatment success.

Highlights • MR-guidance enables high precision single-fraction lung SABR delivery. • Breath-hold gating resulted in a mean tracked GTVt coverage of 99.6% during beam-on. • On-table plan adaptation improved PTV coverage, but had little impact on GTV doses. • Improved techniques are needed to allow for consistent MR-tracking of small tumors., Background and purpose Single-fraction stereotactic ablative radiotherapy (SABR) is an effective treatment for early-stage lung cancer, but concerns remain about the accurate delivery of SABR in a single session. We evaluated the delivery of single-fraction lung SABR using magnetic resonance (MR)-guidance. Materials and methods An MR-simulation was performed in 17 patients, seven of whom were found to be unsuitable, largely due to unreliable tracking of small tumors. Ten patients underwent single-fraction SABR to 34 Gy on a 0.35 T MR-linac system, with online plan adaptation. Gated breath-hold SABR was delivered using a planning target volume (PTV) margin of 5 mm, and a 3 mm gating window. Continuous MR-tracking of the gross tumor volume (GTVt) was performed in sagittal plane, with visual patient feedback provided using an in-room monitor. The real-time MR images were analyzed to determine precision and efficiency of gated delivery. Results All but one patient completed treatment in a single session. The median total in-room procedure was 120 min, with a median SABR delivery session of 39 min. Review of 7.4 h of cine-MR imaging revealed a mean GTVt coverage by the PTV during beam-on of 99.6%. Breath-hold patterns were variable, resulting in a mean duty cycle efficiency of 51%, but GTVt coverage was not influenced due to real-time MR-guidance. On-table adaptation improved PTV coverage, but had limited impact on GTV doses. Conclusions Single-fraction gated SABR of lung tumors can be performed with high precision using MR-guidance. However, improvements are needed to ensure MR-tracking of small tumors, and to reduce treatment times.

Background Historically, it is stated that large intracranial tumors, herein defined as a maximum dimension of ≥3 cm or tumor volume ≥14.2 cm3, are not candidates for stereotactic radiosurgery (SRS). We report outcomes of patients with large benign intracranial tumors treated with SRS. Methods With institutional review board approval, we retrospectively identified 74 patients with large benign intracranial tumors (59 meningiomas, 9 vestibular schwannomas, and 6 glomus jugulare tumors) treated with robotic SRS (2007–2018). Patients received definitive SRS in 47.3% of the cases, adjuvant to surgical resection in 44.6%, and salvage after past radiation treatment in 8.1%. A median tumor volume of 16.0 cm3 (range, 10.1–65.5 cm3) received a median dose of 24.0 Gy (range, 14.0–30.0 Gy) in a median of 3 fractions (range, 1–5), for a median single fraction equivalent dose (with alpha/beta of 3) of 14.8 Gy (range, 11.3–18.0 Gy). The Kaplan-Meier estimate of tumor local control (LC) was calculated from date of SRS. Results With a median clinical follow-up of 32.8 months (range, 0.6–125.9 months) and median radiologic follow-up of 28.5 months (range, 0.6–121.4 months), LC was 96.5% (95% confidence interval, 92.4%–100%) at 3 years and 91.7% (95% confidence interval, 87.6%–95.7%) at 5 years. Adverse radiation effect (ARE) was seen in 10 patients (13.5%) at a median of 13.5 months (range, 7.8–34.5 months). ARE occurred in 9% of those with prior treatment compared with 5% who were radiation-naive (P = 0.23). With 236.4 person-years of follow-up, no secondary malignancies were seen. Conclusions Despite the historical adage, we find that SRS provides high rates of LC for these large tumors, with rates of ARE similar to historical reports of SRS for smaller benign tumors.

Introduction Single fraction radiotherapy (SFR) is effective in palliation of symptoms related to advanced cancer. Despite this, several studies have shown that the trend towards multiple fraction treatment (MFR) is largely maintained. Even in patients with limited life expectancy, SFR is significantly underutilized in current practice. Cases description Four patients diagnosed with advanced cancer who developed soft tissue lesions were treated with SFR due to frailty and/or a poor performance status. Conclusion Despite the effectiveness of SFR is well-established in BM, its use in symptoms caused by soft tissue lesions have been underreported. SFR could be a good option for providing palliation in some patients, particularly in those who are frail or have a poor performance status.

Background: Recently a prognostic score that predicts 12-month survival in patients treated with fractionated radiotherapy for painful bone metastases has been developed. Fractionated radiotherapy might cause unnecessary burden for patients with limited survival, thus estimation of survival is clinically relevant. The purpose of the present study was independent external validation of the new score and, in addition, its application in patients who received single fraction irradiation, a convenient option currently endorsed in several guidelines. Methods: We conducted a retrospective analysis of 270 patients, including 24% who had received single fraction irradiation. The three-tiered score was assigned as described in the development study, and included age, performance status and primary tumor type. Additional prognostic factors not studied in the development cohort, such as the Glasgow prognostic score (GPS) and presence of liver metastases, were included in this validation study. Results: The three-tiered score was valid in this independent cohort (12-month survival rates were 7%, 30% and 71%, respectively, P = 0.0001). Its performance and validity were also confirmed in the single fraction radiotherapy group. Three additional prognostic factors were significant in the multivariate analysis and may therefore contribute to decision making. Conclusions: Irrespective of fractionation, the score based on age, performance status and primary tumor type provides a readily available estimate of 12-month survival. J Clin Med Res. 2020;12(2):90-99 doi: https://doi.org/10.14740/jocmr4060

Bone metastases are a frequent and important source of morbidity in cancer patients. Stereotactic body radiation therapy (SBRT) is an established treatment option for local control and pain relief of bone metastases, and it is increasingly used as upfront treatment, postoperative consolidation or salvage treatment after prior RT. However, heterogeneity of dose schedules described in literature represents a severe limitation in the definition of the role of SBRT as a standard of care. No consensus is available on the use of single versus multiple fraction SBRT for bone metastases. Advantages of single-fraction SBRT include shorter overall duration of treatment, absence of inter-fraction uncertainty, improved compliance, theoretical increased efficacy, and lower costs. However, caution has been advised due to reports of severe late toxicities, in particular, vertebral collapse fracture (VCF). The aim of this paper is to review dose fractionation and indications for the management of bone metastases using SBRT.

Introduction: Patients with severe complications of non-malignant haematological disease are considered as candidates for curative treatment with an allogenic bone marrow transplant (ABMT). A non-myeloablative conditioning regimen is used; consisting of an alkylating agent and single fraction total body irradiation (SFTBI) at a dose of 2-4.5 Gy (dose rate 150mu/min). This is distinct from high dose fractionated total body irradiation (TBI) used in a myeloablative conditioning regimen; for which the late effects are well documented. There is however no dedicated study on the late effects associated with low dose SFTBI. Methods: We undertook a single institution study focusing on patient reported outcomes after SFTBI (January 2003 – January 2019) delivered more than 1-year previously, prior to an AMBT in patients aged under 16-years for non-malignant haematological conditions. A 19-point questionnaire was conducted with study subjects over the phone. The primary outcome was late effects as reported by patients. Secondary outcomes were patient demographics. Results: Fifty patients were screened, 31 were invited to take part and 24 consented to participate. Pulmonary toxicity was the most common visceral effect reported (5 patients), followed by kidney (3) and cardiac (2). No patients reported cataracts, diabetes or secondary malignancy. Two patients were on sex hormone replacement although no evidence of female menstrual delay was demonstrated. The majority (21) were enrolled in mainstream schools. Conclusion: Late effects do occur after SFTBI, but are mild and occur less frequently compared to high dose TBI. The consent process with children/parents prior to SFTBI should reflect this.

Background During the novel coronavirus disease 2019 (COVID-19) pandemic, cancer centers considered shortened courses of radiotherapy to minimize the risk of infectious exposure of patients and staff members. Amidst a pandemic, the process of implementing new treatment approaches can be particularly challenging in larger institutions with multiple treatment centers. We describe the implementation of single-fraction (SF) lung stereotactic ablative radiotherapy (SABR) in a multicenter provincial cancer program. Materials and Methods British Columbia, Canada has a provincial cancer program with six geographically distributed radiotherapy centers serving a population of 5.1 million, over 944,735 square kilometers. In March 2020, provincial mitigation strategies were developed in case of reduced access to radiotherapy due to the COVID-19 pandemic. SF lung SABR was identified by the provincial lung radiation oncology group as a mitigation measure supported by high-quality randomized evidence that could provide comparable outcomes and toxicity to existing fractionated SABR protocols. A working group consisting of radiation oncologists and medical physicists reviewed the medical literature and drafted consensus guidelines that were reviewed by a group of center representatives as a component of provincial lung radiotherapy mitigation strategic planning. Individual centers were encouraged to implement SF lung SABR as their resources and staffing would allow. Centers were then surveyed about barriers to implementation. Results On March 24, 2020, a working group was created and consensus guidelines for SF lung SABR were drafted. The final version was approved and distributed by the working group on March 26, 2020. The provincial lung radiotherapy mitigation strategy group adopted the guidelines for implementation on April 1, 2020. Implementation was completed at the first center on April 27, 2020. Barriers to implementation were identified at five of six centers. Two centers in regions with disproportionately high COVID-19 cases described inadequate staffing as a barrier to implementation. One center encountered delays due to pre-scheduled commissioning of new treatment techniques. Three centers cited competing priorities as reasons for delay. As of May 2021, two centers had active SF lung SABR programs in place, three centers were in the process of implementation, and one center had no immediate plans for implementation due to ongoing resource issues. Conclusion SF lung SABR was adopted by a provincial cancer program within weeks of conception through rapid communication during the development of COVID-19 pandemic mitigation strategies for radiotherapy. Although consensus guidelines were written and approved in an expedited timeframe, the completion of implementation by individual centers was variable due to differences in resource allocation and staffing among the centers. Strong organizational structures and early identification of potential barriers may improve the efficiency of implementing new treatment initiatives in large multicenter radiotherapy programs.

Background In the treatment of spinal metastases, stereotactic body radiotherapy (SBRT) delivers precise, high‐dose radiation to the target region while sparing the spinal cord. A range of doses and fractions had been reported; however, the optimal prescribed scheme remains unclear. Methods Two reviewers performed independent literature searches of the PubMed, EMBASE, Cochrane Database, and Web of Science databases. Articles were divided into one to five fractions groups. The Methodological Index for Non‐randomized Studies (MINORS) was used to assess the quality of studies. Local control (LC) and overall survival (OS) were presented for the included studies and a pooled value was calculated by the weighted average. Results The 38 included studies comprised 3,754 patients with 4,731 lesions. The average 1‐year LCs for the one to five fractions were 92.7%, 84.6%, 86.8%, 82.6%, and 80.6%, respectively. The average 1‐year OS for the one to five fractions were 53.0%, 70.4%, 60.1%, 48%, and 80%, respectively. The 24 Gy/single fraction scheme had a higher 1‐year LC (98.1%) than those of 24 Gy/two fractions (85.4%), 27 Gy/three fractions (84.9%), and 24 Gy/three fractions (89.0%). The incidence of vertebral compression fracture was 10.3%, with 10.7% in the single‐fraction group and 10.1% in the multi‐fraction group. The incidence of radiation‐induced myelopathy was 0.19%; three and two patients were treated with single‐fraction and multi‐fraction SBRT, respectively. The incidence of radiculopathy was 0.30% and all but one patient were treated with multi‐fraction SBRT. Conclusions SBRT provided satisfactory efficacy and acceptable safety for spinal metastases. Single‐fraction SBRT demonstrated a higher local control rate than those of the other factions, especially the 24 Gy dose. The risk of vertebral compression fracture (VCF) was slightly higher in single‐fraction SBRT and more patients developed radiculopathy after multi‐fraction SBRT., Single‐fraction SBRT demonstrated a higher local control than other factions, especially with 24Gy dose. The risk of VCF was slightly higher in single‐fraction SBRT and more patients developed radiculopathy after multi‐fraction SBRT.

For patients with advanced cancer diagnosed with metastatic epidural spinal cord compression (MESCC), radiation therapy can be an appropriate and effective strategy to preserve neurologic function and improve pain (1-3). However, these patients may also have poor performance status and/or limited prognoses (4), and multiple daily treatments using standard fractionation radiation therapy may impose substantial treatment burdens for patients and their caregivers.

Background Patients with multiple myeloma (MM) are living longer than ever before thanks to new therapies. As a consequence, radiation therapy (RT) is increasingly important in the management of bone lesions from MM. Current American Society for Radiation Oncology guidelines recommend greater usage of 8 Gy in 1 fraction for treatment of these lesions. The objective of this study is to analyze utilization of 8 Gy in 1 fraction for treatment of MM bone lesions in the United States utilizing the National Cancer Data Base (NCDB). Materials and Methods The NCDB was used to identify patients with MM treated with palliative RT for painful bony lesions in the period between 2004 and 2014. Utilization rate of RT in this patient population as well as single-fraction (SFRT) versus multiple-fraction RT (MFRT) was compared according to demographic, socioeconomic, and logistic details. Results A total of 95,190 patients met our inclusion criteria. Of these, 10,261 (10.8%) patients received RT, and a total of 243 (2.4%) of these patients received SFRT over the 10-year period. There was an 11.73% annual increase (P = .0001) in SFRT utilization from 2004 to 2014. Older age, black race, longer distance from the treatment facility, lower degree of education, treatment at an academic or integrated healthcare network, worse comorbidities, and more recent diagnoses were all associated with increased usage of SFRT. Conclusion SFRT for the management of MM painful bony metastases remains underutilized. Trends show that radiation oncologists do not appear to be changing their approach to treating this disease.

Background/aim High-dose-rate interstitial brachytherapy (iBT) has been shown to provide high tumor control rates in the treatment of primary or secondary malignancies at various sites. The objective of this study was to evaluate the efficacy and safety of image-guided iBT in patients with metastatic renal cell carcinoma (mRCC). Materials and methods A total of 14 patients with a cumulative number of 54 unresectable RCC liver metastases after treatment with computed tomography (CT)- or open magnetic resonance imaging (MRI)-guided iBT using an iridium-192 source (single fraction irradiation) were included in this retrospective study. Results Local tumor control rate was 92.6% during a median follow-up of 10.2 months (range=2.4-73.6 months). Median progression-free survival after iBT was 3.4 months (range=1.0-27.8 months). Median overall survival was 51.2 months (range=10.2-81.5 months). No severe adverse events (grade 3 or more) were recorded. Conclusion Image-guided iBT is a safe and feasible treatment in patients with mRCC.

Background: Patients with advanced non-small cell lung cancer (NSCLC) are candidates for different types of treatment, including chemotherapy and radiotherapy or supportive care. Despite the fatal prognosis in advanced disease, many experienced radiation oncologists will apply radiation at low doses with the intention of palliative care. Methods: We used an extensive database of medical patients diagnosed with NSCLC, treated with palliative radiotherapy at the Oncology Centre in Bydgoszcz, from June 1998 to December 2013. A group of 3202 patients was divided into subgroups: Group A)1762 patients irradiated on the lung tumor (without distant metastases): Total dose: A1) 6Gy/1 fr.(n=19); A2) 8Gy/1fr.(n=276); A3) 20Gy/5fr.(n=1349); A4) 30Gy/10fr.(n=118). Group B) 548 patients irradiated on the central nervous system (CNS) metastases: B1) 20Gy/5fr.(n=476); B2) 30Gy/10fr.(n=72). Group C) 892 patients irradiated on the bone metastases: C1) 8Gy/1fr.(n=452); C2) 10Gy/1fr.(n=30); C3) 20Gy/5fr.(n=341); C4) 30Gy/10fr.(n=69). Results: Patients with irradiation of a lung tumor: The longest OS was observed in the group of patients irradiated with doses of 20 Gy (76%) and 30 Gy (7%). Patients with irradiation of bone metastases: No significant differences in OS were observed between the employed fractionation regimens. Patients with irradiation of CNS metastases: The choice of a higher dose of radiation therapy did not demonstrate differences in median OS values compared to a lower dose. Conclusions: The patients who were prescribed single fraction palliative radiotherapy did not have poorer prognoses or experience shorter survival than patients who were prescribed multi-fraction pRT in the case of lung tumor, brain metastases and bone metastases.

Purpose/Objective(s) Bone metastases are a common oncologic development occurring in approximately 60-70% of patients with advanced malignancies. Historically, bone directed radiotherapy at doses of 30 Gy delivered over 10 daily fractions have been commonly employed. However, prospective randomized data suggests equivalent pain relief with shorter course regimens. As such, the ASTRO Choosing Wisely Campaign was created in an effort to encourage clinicians to consider shorter course palliative regimens in patients with uncomplicated bone metastases who have a limited prognosis. We performed a retrospective analysis of our large, integrated health system in an effort to assess utilization patterns of short course and single fraction radiotherapy regimens over the last 5 years. Materials/Methods We queried our internal radiation oncology electronic medical record (MOSAIQ®) from 2016-2020 for patients with bone metastasis who received palliative bone-directed radiotherapy in our network. Patients receiving Medicare approved palliative courses of radiation (30 Gy/10 fractions, 24 Gy/6 fractions, 20 Gy/5 fractions, 8 Gy/1 fraction) were included, as well as, patients receiving > 10 fractions. Treatment site was defined as academic (n = 2) versus community (n = 12). Short course treatment was defined as radiation treatment courses of ≤ 6 fractions, whereas long course included patients receiving ≥ 10 fractions. Patients were subdivided into quartiles based upon age and site of disease (spine, hip/pelvis, extremity, and other). Physicians were grouped according to their year of radiation oncology residency completion (before versus after 2010). Multivariable logistic regression analysis was completed to identify predictors of short course and single fraction treatment. Results We identified 1,004 patients with 1,768 bony metastatic lesions meeting the above criteria. The median patient age was 68 years (Interquartile range: 61-76 years). The spine was the most commonly treated site (46%) followed by pelvis/hip (26%), extremity (15%), and other (13%). Use of short course treatment increased over time from 40% in 2016 to 50% in 2020. Single fraction treatment also increased over time from 7% in 2016 to 11% in 2020. Predictors of short course treatment included: treatment at an academic center, more recent treatment year, patient age > 76 years old, non-spine anatomic site. Predictors of single fraction treatment included: treatment at an academic center, treating physician residency completion after 2010, patient age > 76 years old, and treatment to extremity or other site. Conclusion Rates of short course and single fraction bone-directed radiotherapy utilization increased within our integrated health system over time. Treatment receipt at an academic center was associated with both short course and single fraction regimens. Physicians completing residency after 2010 were more likely to deliver single fraction therapy.

PURPOSE/OBJECTIVE(S) The purpose of this analysis was to investigate whether the combination of external beam radiotherapy (EBRT) and brachytherapy boost (EBRT+BT) is superior to EBRT alone in terms of biochemical control (BC) in the management of intermediate (IR) and high risk (HR) prostate cancer (PC) patients and whether the difference is associated with local biologically effective dose (BED) escalation. MATERIALS/METHODS We investigated 1123 patients treated for IR (24.8%) or HR PC (75.2%) with EBRT (90.7%) or EBRT+BT (9.3%) at one institution between 2003 and 2012. Kaplan-Meier curves were used to calculate biochemical control. Log-rank testing and Cox regression were used to compare results between groups. BED was calculated using α/β of 3 for PC. The majority of patients treated with EBRT received 76 Gy in 2 Gy fractions (79%, median BED = 126.7 Gy) or equivalent. The majority of patients treated with EBRT+BT received either 54 Gy in 2 Gy fractions followed by 10-11 Gy single fraction BT boost (47.6%, median BED = 133.3 Gy), or 46-50 Gy in 2 Gy fx followed by 20-21 Gy two fraction BT boost (51.4%, median BED = 171.2 Gy). RESULTS The median age of the patients was 68-years. The 5-year BC was 79%. There was no statistically significant difference in BC between patients treated with EBRT or BT in IR (P = 0.74) and HR (P = 0.73) PC groups. There was a significant difference between patients receiving lower and higher BED (> 135 Gy) fractionation schemes in favor of higher BED, both for IR (5-y BC of 100% vs 81%, P = 0.02) and HR group (5-y BC of 92% vs 77%, P = 0.02). The BED was inversely associated with risk of BC in univariate analysis (HR = 0.98; CI95% 0.97-0.99; P < 0.01), and remained an independent prognostic factor in the multivariate analysis (HR = 0.97; CI95% 0.96-0.99; P < 0.01) along with Gleason Grade Groups score (HR = 1.18; CI95% 1.05-1.32; P < 0.01). CONCLUSION The combination of EBRT and BT boost has the potential to significantly improve biochemical control in IR and HR prostate cancer patients through local BED escalation. The improvement in BC was observed in patients receiving higher BED, as well as a significant association between BED and risk of biochemical failure.

Many cancers result in metastasis in the spinal vertebrae, which can cause pain, neurological disability, and reduce quality of life [1,2]. To improve the local disease control and relieve symptoms...