MMOD-14 IMPACT OF SYSTEMIC THERAPY ACTIVITY ON BRAIN METASTASIS OUTCOMES IN A FEMALE AND HISPANIC-DOMINANT LUNG CANCER COHORT TREATED WITH STEREOTACTIC RADIOSURGERY

Abstract We analyzed the impact of systemic therapy on lung cancer (LC) patients treated with stereotactic radiosurgery (SRS) for brain metastasis (BM) in terms of objective response, intracranial progression-free survival (iPFS), and overall survival (OS). Response was calculated using chi-square analysis with adjusted residuals, while iPFS and OS were computed using the Kaplan-Meier method. A total of 426 BMs in 91 LC patients from 01/2017-07/2022 were included. The median age was 66 years (interquartile range [IQR] 58-73), in our predominantly female (57.1%) and Hispanic (76.9%) population. The median number of BMs was 4 (IQR: 2-8). Systemic therapy was grouped as no switch (no change; 15 patients, 34 BMs) or switch (change from pre- to post-SRS), with the latter classified as a switch-up (increased CNS activity; 76 patients, 392 BMs) or switch-down (decreased CNS activity; 0 patients). At first radiographic evaluation, rates of complete response, partial response, stable disease, or progressive disease were similar (switch-up [%]/no switch [%]) in 32.7%/50.0%, 23.0%/11.8%, 38.3%/32.4%, and 6.1%/5.9%, p