Clinical outcomes of patients with brain metastases from colorectal cancer treated with stereotactic radiosurgery

Abstract Background Brain metastases from gastrointestinal primaries, including colorectal cancer (CRC), have been shown to respond less favorably to stereotactic radiosurgery (SRS) compared with other primary sites. We report institutional outcomes of patients with brain metastases from CRC treated with SRS. Methods Patients with CRC who underwent SRS for brain metastases between 1989 and 2021 were retrospectively reviewed. The primary endpoint was local failure (LF); secondary endpoint was overall survival (OS). LF was estimated using the Cumulative Incidence Function with death as a competing risk. OS was analyzed using the Kaplan-Meier method. Predictors of LF were assessed using competing risk regression. Results The study population comprised of 110 patients with primary CRC with 207 brain metastases. Median follow-up was 5.2 months (range: 0.4-124). Median OS was 5.8 months (range: 0.5-71.2). Fifty-seven patients with 114 lesions (55%) were female. Median Karnofsky Performance Status at the time of treatment was 80 (range: 40-100). Median tumor diameter was 1.6 cm (range: 0.2-5.5). Median prescription dose was 24 Gy (range: 11-36) delivered in a median of 1 fraction (range: 1-3). Cumulative incidence of LF at 3, 6, and 12 months was 9.7%, 22%, and 25%, respectively. OS at 3, 6, and 12 months was 81%, 49%, and 24%, respectively. On univariate analysis, age was a significant predictor (P  Conclusion Patients with brain metastases from CRC demonstrate higher LF after SRS compared with other primary sites, highlighting the radioresistant biology of this histology.