RADI-27. ROLE OF STEREOTACTIC RADIOSURGERY IN THE CARE OF PATIENTS WITH >/= 25 CUMULATIVE BRAIN METASTASES

Abstract INTRODUCTION: Stereotactic radiosurgery (SRS) is an accepted treatment for multiple brain metastases. However, the upper limit of the number of brain metastases over the course of care suitable for this approach is controversial. METHODS: From a review of our prospective registry, 48 patients treated with SRS for ≥ 25 brain metastases in either single or multiple sessions between 2013 and 2019 were identified. Patient, tumor, and treatments characteristics were evaluated. Clinical outcomes and overall survival (OS) were analyzed. RESULTS: Thirty-one females (64.6%) and 17 males (35.4%) with a median age of 56 years (25–91) were included. Primary diagnoses included lung (n=23, 47.9%), breast (n=13, 27.1%), melanoma (n=8, 16.7%), and other (n=4, 8.33%). Initial median GPA index was 2 (0.5–3). Nine patients (18.8%) had received whole brain radiation therapy (WBRT) prior to first SRS treatment, with a median dose of 35Gy (30–40.5Gy). Ten patients (20.8%) received WBRT after initial SRS, with a median dose of 30Gy (20-30Gy). Thus, only 19 patients (40%) ever received WBRT. Median number of radiosurgeries per patient was 3 (1–12). Median number of cumulative tumors irradiated was 31 (25–110). Median number of tumors irradiated at first SRS was 10 (1–35). Median marginal dose for the largest tumor per session was 16Gy (10-21Gy). Median SRS total tumor volume was 6.8cc (0.8–23.4). Median follow-up since initial SRS was 16 months (1–71). At present, 21 (43.7%) are alive. Median OS from the diagnosis of brain metastases was 31 months (2–97), and OS from the time of first SRS, 22 months (1–70). Median KPS at first SRS and last follow-up was the same (90). Sixty-three percent did not require a corticosteroid course. CONCLUSION: In selected patients with a large number of cumulative brain metastases (≥ 25), SRS is effective and safe. Therefore, WBRT may not be required in this population.