RADT-76. SURVIVAL DISADVANTAGE WITH BETA-BLOCKER USE IN MELANOMA BRAIN METASTASES

Abstract BACKGROUND Recent observational studies increasingly support the off-label use of β-blockers (BB) as adjuvant therapy that may enhance survival in cancer patients. However, their effect on survival and intracranial progression in melanoma brain metastases (MBM) remains unclear. This study evaluates the association between BB use and outcomes in MBM patients treated with immunotherapy and Gamma Knife Radiosurgery (GKRS). METHODS This retrospective study includes 234 patients with MBM treated between 2011 and 2024. Among them, 146 were on concomitant BB therapy. To address baseline differences, we performed two 1:1 propensity score matchings: Cohort 1 - any BB vs no BB (n = 172) - and Cohort 2 - non-selective BB vs no BB (n = 32). Outcomes included overall survival (OS), local progression (LP), and distant brain metastasis failure (DBMF). Kaplan–Meier curves and Cox proportional hazards models were utilized. RESULTS There were no significant differences in baseline demographics or treatment parameters among the matched cohorts. In the unmatched cohort, patients not taking BB had higher median OS at 12, 24, 36, and 48 months (66%, 52%, 50%, and 45%, respectively), compared to the BB group (52%, 46%, 42%, and 38%, respectively). In Cohort 1, median OS was lower in BB users but did not show significance (p = 0.45). BB users, however, had a significantly shorter median time to DBMF compared to non-users (5.4 vs 13.2 months; p = 0.0055). In Cohort 2, non-selective BB use did not significantly impact LP (p = 0.64) or median time to DBMF (p=0.27). CONCLUSIONS Although BB use did not impact OS or LP, it was associated with decreased time to distant metastasis failure after propensity score matching. These findings suggest a potential adverse association with intracranial disease control. Prospective studies are warranted to elucidate these interactions.