The Role of Stereotactic Radiosurgery in Patients With Brain Metastases From Colorectal Cancers

BACKGROUND AND OBJECTIVES: The role of stereotactic radiosurgery (SRS) in patients with brain metastases (BMs) from colorectal cancers (CRCs) has not been established. The authors present a single-institution experience of patients with CRC who underwent SRS with metastatic brain spread. METHODS: We retrospectively analyzed 111 patients with metastatic CRC (64 female, 57.7%), with 449 BMs treated with Gamma Knife SRS between 2000 and 2022. The median age during SRS was 63 years (range: 28-86), and the median Karnofsky Performance Scale was 80 (range: 60-100). The primary sites were colon (85 patients, 76.6%) and rectal (26 patients, 23.4%). Three patients underwent hypofractionated 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: 13-20). RESULTS: The median patient survival after SRS was 7 months (range: 1-174). Ninety-eight (88.3%) patients expired at last follow-up and 15 patients (15.3%) died related to progressive intracranial disease. A Karnofsky Performance Scale of <80 at SRS presentation ( P = .02, hazard ratio [HR]: 0.6, 95% CI: 0.4-0.9) and no previous surgical resection ( P < .01, HR: 0.4, 95% CI: 0.3-0.7) were associated with inferior overall survival using multivariate analysis. Seventeen patients (15.3%) had documented local tumor progression after SRS, at a median time of 7 months (range: 3-34) between SRS and progression. Twenty-six patients (23.4%) developed new BMs at a median of 5 months (range: 2-26) between SRS and new tumor detection. Less than three BMs at SRS presentation ( P = .02, HR: 2.6, 95% CI: 1.2-5.6) were associated with better distant tumor control on multivariate analysis. The incidence of adverse radiation effects was 5.4%. CONCLUSION: SRS effectively controls BMs from CRC with low risk of treatment-related toxicity. During follow-up, the development of additional metastases can be safely treated by repeat SRS.