Metastasis directed treatment of brain metastases from colorectal cancer - a Danish population-based cohort study

Background: Brain metastases (BMs) are an uncommon presentation of metastatic colorectal cancer (mCRC) with reported incidence of about 2-4%. Today, there is an increased awareness towards a metastasis directed treatment approach with either surgical resection, stereotactic radiotherapy (SRT) or both. We examined patient characteristics and survival for patients treated with a localized modality for BM from CRC in a nationwide population-based study.Methods: A registry-based cohort study of all patients with a resected primary colorectal cancer and localized treatment of BM during 2000-2013. We computed descriptive statistics and analysed overall survival by the Kaplan-Meier method and Cox regression.Results: A total of 38131 patients had surgery for a primary CRC and 235 patients were recorded with a metastasis directed treatment for BM, comprising resection alone (n = 158), SRT alone (n = 51) and combined resection and SRT (n = 26). Rectal primary tumor (48.9% vs. 36.2%, p < .001) and lung metastasectomy (11.9 vs 2.8%, p < .001) were more frequent in the BM group. The median survival of patients receiving localized treatment for BM was 9.6 months (95% confidence interval (CI) 7.2-10.8). The 1- and 5-year overall survival were 41.7% (95% CI 35-48%) and 11.2% (95% CI 6.9-16.3%). In multivariate analysis, nodal stage was associated with increased mortality with a hazard ratio of 1.63 (95% CI 1.07-2.60, p = .03) for N2 stage with reference to N0.Conclusion: We report a median overall survival of 9.6 months for patients receiving localized treatment for BM from CRC. Lung metastases and rectal primary tumor are more common in the population treated for BM.