RADT-13. CLINICAL OUTCOMES COMPARING RADIOSURGERY TECHNIQUES FOR MANAGING LARGE BRAIN METASTASES

Abstract INTRODUCTION Large brain metastases (BM) are associated with poor local control single-fraction radiosurgery (SRS) alone. We sought to compare outcomes various alternative management strategies assess disease rates. METHODS Consecutive patients diagnosed BM ≥ 2 cm in maximum diameter between 3/2019-2/2021 and treated at a single tertiary institution were included. Primary endpoints included freedom-from-local-failure (FFLF) calculated on per-lesion basis from the date of initial intervention failure, overall survival (OS). Kaplan-Meier analysis log-rank test used. RESULTS 86 102 large met inclusion criteria. The median age was 66 years (range: 31-98), KPS 90 (50-100), 57.8% female. most common primary tumor lung 40 (39.2%) lesions. volume 9.7 cm3 (2.1-35.5 cm3) 3.3 (2.9-5.6 cm). 37 (36.3%) lesions staged-SRS, 31 (30.4%) resection postoperative-SRS, 21 (20.6%) preoperative-SRS resection, 13 (12.7%) fractionated-SRS (FSRS). Lesions or postoperative-SRS higher rates no- stable-extracranial disease, larger volumes (preoperative-SRS: 14.5 [4.2-33.1]; postoperative-SRS: 18.0 [2.5-35.5]; FSRS: 5.9 [2.1-24.6]; staged-SRS: 6.5 [2.2-27.8]).With follow-up 15.6 months, 12 (11.8%) failures 42 (41.2%) deaths occurred. 1-year FFLF OS for entire cohort 85.6% (95% CI: 77.9-93.3%) 64.4% 54.7-74.1%), respectively. (p=0.542)/OS (p=0.043) 94.1%/100% preoperative-SRS, 84.0%/43.4% 81.8%/74.1% FSRS, 81.5%/63.4% CONCLUSION Although limited by patient numbers, selection bias, high attrition rate, had numerically favorable outcomes, supporting this approach BM. Prospective evaluation is warranted determine optimal strategy.