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Purpose: Stereotactic body radiation therapy can be an effective treatment for oligometastases. However, safe delivery of ablative radiation is frequently limited by the proximity of mobile organs sensitive to high radiation doses. The goal of this study was to determine the feasibility, safety, and disease control outcomes of stereotactic magnetic resonance-guided adaptive radiation therapy (SMART) in patients with abdominopelvic oligometastases., Methods and Materials: We identified 101 patients with abdominopelvic oligometastases, including 20 patients enrolled on phase 1 protocols, who were consecutively treated with SMART on a 0.35T magnetic resonance linear accelerator (MR linac) at a single institution from October 2019 to September 2021. Local control and overall survival were analyzed using the Kaplan-Meier method., Results: Overall, 114 tumors were treated. The most common histology was prostate adenocarcinoma (60 tumors [53.5%]), and 65 sites (57.0%) were centered in the pelvis. Ninety-one sites (79.8%) were treated to 8 Gy × 5, and 49 (43.0%) were treated with breath-hold respiratory gating. Online adaptation resulted in a clinically significant improvement in coverage or organ sparing in 86.6% of delivered fractions. The median time required for adaptation was 24 minutes, and the median time in the treatment room was 58 minutes. With median follow-up of 11.4 months, the 12-month local control was 93% and was higher for prostate adenocarcinoma versus other histologies (100% vs 84%; P = .009). The 12-month overall survival was 96% and was higher for prostate adenocarcinoma versus other histologies (100% vs 91%; P = .046). Three patients (3.0%) developed grade 3 toxic effects (colonic hemorrhage at 3.4 months and urinary tract obstructions at 10.1 and 18.4 months, respectively)., Conclusions: In this study, SMART was feasible, safe, and effective for delivering ablative radiation therapy to abdominopelvic metastases. Adaptive planning was necessary in the large majority of cases. The advantages of SMART warrant its further investigation as a standard option for the treatment of abdominopelvic oligometastases., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: Limited data exist to guide optimal patient selection and treatment of bone metastases with curative intent despite the increasing application of stereotactic body radiation therapy (SBRT) for oligometastatic (OM) disease control and reirradiation (Re-RT)., Methods and Materials: Clinical characteristics for 434 patients consecutively treated with bone SBRT at a single institution from March 2011 to June 2020 were analyzed by OM, spine, and nonspine bone using Cox regression to determine association with local control (LC), progression-free survival (PFS), and overall survival (OS), and the Kaplan-Meier method to estimate PFS and OS., Results: Most patients had prostate (39%) or breast/lung (21%) cancer and 1 to 3 lesions (96%), with 651 lesions (spine 63%) treated for Re-RT (12%) or OMD (88%), including synchronous (10%), metachronous (28%), repeat (27%), or induced (23%) states as defined by The European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer criteria. Biologically effective dose (BED 10 ) ≥50 (hazard ratio, 0.68; 95% confidence interval, 0.48-0.96; P < .03) predicted improved LC among OM lesions and planning target volume (PTV) ≥150 cc (hazard ratio, 1.94; 95% confidence interval, 1.02-3.70; P < .04) predicted worse LC for nonspine bone. Prostate histology, performance status (PS) 0 to 1, and metastasis-free interval ≥2 year predicted improved PFS and OS (P < .05). Metachronous, synchronous, or repeat OM had higher PFS and OS (P ≤ .001) than induced OM. With median follow-up 25.7 months, 1- and 2-year PFS was 63% and 47% for OM and 36% and 25% for Re-RT; 1- and 2-year OS was 87% and 73% for OM and 58% and 43% for Re-RT. Acute toxicities included grade 1 to 2 pain flare (9%) and fatigue (14%). Late toxicities included fracture (1%) for OM and myelopathy (2.5%) or nerve pain (1.2%) for Re-RT., Conclusions: BED 10 ≥50 for OM and PTV <150 cc for nonspine bone lesions was associated with improved LC. Prostate histology, PS 0 to 1, metastasis-free interval ≥2 years, and metachronous, synchronous, or repeat presentations per The European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer criteria predicted improved PFS and OS among OM patients treated with bone SBRT., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: We retrospectively evaluated outcomes after radiation therapy for patients with oligoprogression on immune checkpoint inhibitors (ICI)., Methods and Materials: We identified patients irradiated to ≤5 progressive lesions while receiving ICI between 2010 and 2020. We excluded patients whose systemic therapy was switched after radiation but before progression. We evaluated predictors of local control (LC), progression-free survival (PFS) and overall survival (OS)., Results: We screened 1423 patients and identified 120 who were eligible; the most common histologies were lung cancer (n = 59) and melanoma (n = 36). The median number of oligoprogressive lesions was 1. For the median LC of irradiated oligoprogressive lesions, PFS and OS were not reached at 6.41 (4.67-7.66) and 29.80 (22.54-43.33) months, respectively. Tumor histology, radiated site, or radiation modality were not associated with LC, PFS, or OS. Local response to radiation (P < .0001) and radiation of newly developed lesions (P = .02) were associated with LC. Predictors of PFS on univariate and multivariate analyses were best response to radiation (P = .006) and high programmed death ligand 1 tumor proportion score (P = .02). On multivariate analyses, OS was associated with cumulative oligoprogressive lesion volumes (P = .02) and duration of ICI before oligoprogression (P = .03)., Conclusions: Promising outcomes were observed among patients irradiated for oligoprogression on ICI, especially those with a favorable local response, high tumor programmed death ligand 1 expression, and those receiving ICI for longer periods before oligoprogression. These data can help identify patients well suited for radiation therapy versus those who should switch systemic treatment., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: To explore whether a subgroup of men with unfavorable-risk prostate cancer (PC) exists in whom high-dose radiation therapy (RT) alone is sufficient to avoid excess PC death due to competing risk from cardiometabolic comorbidity., Methods and Materials: This was a cohort study of 7399 men in whom comorbidity (including congestive heart failure, diabetes mellitus, or myocardial infarction) was assessed and recorded with T1-3NxM0 PC treated with brachytherapy with or without neoadjuvant RT, October 1997 to May 2013 at a single providing institution. Cox and competing risks regression analyses were used to assess whether men with unfavorable-intermediate/high-risk versus favorable-intermediate/low-risk PC were at increased risk of PC-specific, all-cause, or other-cause mortality (PCSM, ACM, OCM), adjusting for number of comorbidities, age at and year of brachytherapy, RT use, and an RT treatment propensity score., Results: After a median follow-up of 7.7 years, 935 men died: 80 of PC and 855 of other causes. Among men with no comorbidity, PCSM risk (adjusted hazard ratio [AHR] 2.74 [95% confidence interval (CI) 1.49-5.06], P=.001) and ACM risk (AHR 1.30 [95% CI 1.07-1.58], P=.007) were significantly increased in men with unfavorable-intermediate/high-risk PC versus favorable-intermediate/low-risk PC, with no difference in OCM (P=.07). Although PCSM risk was increased in men with 1 comorbidity (AHR 2.87 [95% CI 1.11-7.40], P=.029), ACM risk was not (AHR 1.03 [95% CI 0.78-1.36], P=.84). Neither PCSM risk (AHR 4.39 [95% CI 0.37-51.98], P=.24) or ACM risk (AHR 1.43 [95% CI 0.83-2.45], P=.20) was increased in men with 2 comorbidities., Conclusions: To minimize death from PC, high-dose RT alone may be sufficient treatment in men with 2 or more cardiometabolic comorbidities and unfavorable-intermediate- and high-risk PC., (Copyright © 2016 Elsevier Inc. All rights reserved.)