RADT-43. RADIOSURGERY FOR BRAIN METASTASES FROM GYNECOLOGICAL PRIMARIES: AN INSTITUTIONAL PERSPECTIVE OF 58 METASTATIC LESIONS

Abstract Stereotactic radiosurgery (SRS) is being increasingly employed in the treatment of brain metastases. The evidence of radiological response of metastatic lesions from gynecological primary is lacking in literature. To assess the response rate of metastatic lesions to gamma knife SRS over a longitudinal follow-up period, a single centre prospectively maintained database was analysed retrospectively from 2014 to 2024. Lesion volumes were contoured at each follow up scan using Leksell Gammaplan software. Response assessment in neuro-oncology (RANO) criteria was used to assess radiological tumor response rates. Fifteen patients with 58 lesions were included. Average duration of radiological follow-up available was 16.7 months. The primary gynecological source of brain metastases in patients were cervical(n=4), ovarian(n=7), endometrial(n=3) and vulvar (n=1). Single fraction SRS was used for 49 lesions (range 16-20 Gy) and hypofractionated SRS for 9 lesions (8Gy x 3 to 9Gy x3). Average time to complete response was 9.01 months (range 1-25.7). The average follow-up for lesions with partial response was 12.2 months (range 1 -32) As per RANO criteria, complete response was seen in 33(56.9%) lesions and partial response in 25(43.1%). At 6month follow up, complete response was seen in 58.49% (n=31) of the lesions available(n=53) for assessment and partial response in 41.51%(n=22). At 18-months, complete response was seen in 66.67%(n=22) and partial response in 33.33%(n=11). Within pathological subgroups, endometrial (60%,n=3) primary showed higher rate of complete response at 6months than ovarian (52.7%,n=19), vulvar (50%, n=1) and cervical (40%,n=6) subgroups. Brain metastases from ovarian primary source were most encountered and endometrial metastases showed highest response rates to SRS. Six month and 18-month response rates were better than previously reported literature.