Brain metastases in colorectal cancer: prognostic factors and survival analysis

Colorectal cancer (CRC) brain metastases (BM) are an uncommon and late event. We aim to investigate the impact of clinical factors, treatment modalities and RAS/BRAF status on the outcomes of CRC patients with BM. We retrospectively analysed CRC patients who developed BM in our centre between January 1997 and June 2017. Clinical factors, treatment modalities, RAS/BRAF status and survival were evaluated. Twenty-eight patients were recorded; 82% had left-sided (LS) CRC and 71% had lung metastases. Median time to BM diagnosis was 36 months (m) and 93% of patients received local treatment of BM (43% whole brain radiotherapy, 50% surgery). Right-sided (RS) CRC showed shorter time to BM, not previously described (9.3 vs 46.6 m for RS and LS CRC, respectively; HR = 4.7, p = 0.006). Median overall survival (mOS) from BM treatment was 9.5 m, better in patients who underwent surgery than those treated with radiotherapy alone (12.1 vs 4.6 m, respectively; HR = 0.3, p = 0.019) and in those without progressive metastatic extracranial disease (7.2 vs 20.9 m, for progressive and non-progressive, respectively; HR = 0.3, p = 0.056). Patients with two or more metastatic extracranial locations showed worse prognosis (5.9 vs 16.3 m, for > 2 vs 0–1, respectively; HR = 3.7, p = 0.015). RAS/BRAF status did not showed prognostic value. Time to BM diagnosis is shorter in RS CRC. The presence of two or more metastatic extracranial locations and progressive metastatic extracranial disease at the time of BM diagnosis could be bad prognosis factors for CRC BM patients.