Cesium-131 collagen “GammaTile” brachytherapy cuts surgical-bed recurrence vs post-op SRT in resected brain mets

Cesium-131 collagen tile-based radiation therapy (TBRT; intraoperative brachytherapy that delivers focal radiation immediately after resection) was compared with standard post-operative stereotactic radiation therapy (SRT) in ROADS, a randomized, open-label, Phase 3 non-inferiority trial across 32 US centers (NCT04365374). In the mITT population of newly diagnosed brain metastasis patients undergoing resection (n=204; 103 R+TBRT vs 101 R+SRT; median follow-up 12.9 months), median time-to–surgical bed recurrence (SBR) was not reached with R+TBRT vs 17.4 months with R+SRT (HR 0.06, 95% CI 0.01–0.46; p=0.0070) and surgical bed recurrence–free survival (SB-RFS) improved (median not reached vs 10.9 months; HR 0.48, 95% CI 0.30–0.76; p=0.0021); overall AEs were similar (79.0% vs 80.7%). For context, post-op cavity SRT is guideline-supported SOC after resection to reduce local recurrence while avoiding WBRT-associated cognitive toxicity, with historical 12-month surgical-bed local control rates commonly in the ~70–90% range depending on series/trial design—so ROADS’ HR=0.06 for time-to-SBR is a notably large effect size that will make readers scrutinize event counts, follow-up maturity, and assessment methodology.