Stereotactic radiosurgery for brain metastases from gastrointestinal primaries: analysis of outcomes

Abstract AIMS Brain metastases from gastrointestinal primaries are uncommon with poor reported outcomes following SRS. We evaluated clinical outcomes for patients diagnosed with metastatic brain tumours from a gastrointestinal primary treated with stereotactic radiosurgery (SRS). METHOD A single institutional retrospective review of patients treated with LINAC-based SRS at our institution between 2017 and 2022. Median survival was calculated from the time of SRS. RESULTS A total of 24 patients were treated with primary malignancy locations as follows: 10 colon, 7 rectum and 7 oesophageal. Median survival was 6.4 months for the overall cohort and 4.5 months for colon, 6.1 months for rectum and 14 months for oesophagus. 44% and 14% of patients had undergone surgical resection with colorectal cancer (CRC) and oesophageal cancer respectively. Median survival in CRC patients receiving SRS post-operatively was 6.8 months compared with 11.5 months for patients with non-gastrointestinal primaries. Time from diagnosis of the primary malignancy to diagnosis of brain metastases showed an inverse correlation with survival: 48 months colon, 21 months rectum and 13 months oesophagus. Compared to oesophageal patients, CRC patients were more likely to have extra-cranial disease at the time of SRS (57% vs. 18%). CONCLUSIONS Survival after SRS to brain metastases from gastrointestinal primaries is poor, but we demonstrate important differences in outcome depending on the location of the primary malignancy. Oesophageal cancer patients had the best survival with colon cancer patients having the worst. Although our findings are likely to influenced by patient selection bias, these differences are worthy of further investigation.