Radiation Oncology

Prospective registry shows low severe toxicity with concurrent biologic therapy and metastasis-directed SRT

In this international registry, 433 patients received 514 cranial or extracranial SRT courses with concurrent biologic cancer therapy (ICIs, small molecules, or mAbs). Severe acute adverse events were infrequent (5.3%), with three grade 5 events, and severe late events occurred in 6.3%, including two grade 5 events. Continuing biologic therapy during SRT was not associated with increased severe acute or late toxicity compared with pausing treatment (odds ratio 2.32; 95% CI, 0.87-6.22). Temporary interruption of biologic therapy during SRT was not linked to worse PFS or OS after adjustment for performance status and histology (hazard ratio 0.81; P = .17). 1

Definitive CRT plus ICIs in LA-NSCLC sharply increases pneumonitis, especially with concurrent ICIs

Among 449 unresectable LA-NSCLC patients, adding ICIs to definitive CRT increased grade ≥2 treatment-related pneumonitis from 9.8% to 30.6% after weighting (P < .001). Concurrent ICIs produced the highest grade ≥2 pneumonitis incidence (51.5%), followed by induction (32.0%) and consolidation (24.2%) use. Grade ≥2 radiation pneumonitis rose to 16.7% with ICIs and peaked at 39.1% in the concurrent subgroup. Independent predictors of grade ≥2 radiation pneumonitis included ICI treatment, gemcitabine-based induction chemotherapy, and higher lung V20 and mean lung dose. Grade ≥2 checkpoint inhibitor pneumonitis (14.2%) was associated with pre-existing interstitial lung disease or emphysema, PD-1 inhibitors, and elevated mean lung dose. 2

Use of invasive mediastinal staging before stage I lung SBRT varies widely and associates with survival

This NCDB analysis identified 34,879 stage I NSCLC patients treated with SBRT at 1,210 hospitals, with 11.5% undergoing invasive mediastinal staging (IMS). Hospital IMS rates ranged from 0% to 100%, with 31.4% of the variation attributable to hospital-level factors rather than case mix. Risk- and reliability-adjusted overall IMS use was low at 15.5%, and patient and tumor characteristics were similar across hospital quintiles. Hospitals with the lowest IMS rates had worse median survival than those with the highest rates (46 vs 54 months; P < .001). 3

Nationwide cohort links PSA relapse timing and Gleason score to prostate cancer death after RT

In 26,634 Swedish men treated with primary radical RT, the 10-year risk of PSA relapse by Phoenix criteria was 25%. Among men who relapsed, 10-year prostate cancer–specific mortality was 35% but varied markedly by Gleason score and relapse timing. Relapse within 18 months carried high mortality, including 52% for Gleason 4+3 and 75% for Gleason 9–10 disease. At one year after RT, Gleason 9–10 relapse conferred roughly fourfold higher prostate cancer death risk than Gleason 6 (86% vs 22%). For relapse occurring 10 years post-RT, mortality differences by Gleason were modest (14% vs 23%), challenging existing EAU relapse-risk groupings. 4