LMAP-19 THE ROLE OF STEREOTACTIC RADIOSURGERY IN PATIENTS WITH BRAIN METASTASES FROM COLORECTAL CANCERS

BACKGROUND AND OBJECTIVES: The role of stereotactic radiosurgery (SRS) for patients with brain metastases from colorectal cancers (CRC) has not been established. The authors present a single-institution experience of CRC patients who underwent SRS with metastatic brain spread. METHODS: We retrospectively analyzed 112 metastatic CRC patients (64 female, 57.14%) with 450 brain metastases that were treated with Gamma Knife SRS between 2000-2022. The median age at SRS was 63 years (range: 28-86) and the median Karnofsky Performance Score (KPS) was 80 (range: 60-100). The primary sites were colon (86 patients, 76.79%) and rectal (26 patients, 21%). Three patients underwent hypo-fractionated SRS (3 sessions) with a median margin dose of 27 Gy (range: 27- 30). All other patients underwent single-session SRS with a median margin dose of 18 Gy (range: 11-20). RESULTS: The median patient survival after SRS was 7 months (range: 1-174). Ninety-eight (87.5%) patients expired at last follow up and 15 patients (15.31%) died related to progressive intracranial disease. KPS < 80 at SRS presentation (p=0.03, HR: 0.63, 95% CI: 0.41-0.96) was associated with inferior overall survival using multivariate analysis. Seventeen patients (15.18%) had documented local tumor progression after SRS, at a median time of 7 months (range: 3-34) between SRS and progression. Twenty-six patients (23.21%) developed new brain metastases at a median of 5 months (range: 2-26) between SRS and new tumor detection. KPS ≥ 80 (p=0.05, HR: 0.96, 95% CI: 0.93-0.99), and < 3 brain metastases at SRS presentation (p<0.01, HR: 3.62, 95% CI: 1.53-8.56) were associated with better distant tumor control on multivariate analysis. The incidence of adverse radiation effects was 5.36%. CONCLUSIONS: SRS effectively controls brain metastases from CRC with a low risk of treatment-related toxicity, allowing patients to focus on primary disease management. During follow-up, the development of progressive or additional metastases can be safely treated by repeat SRS.