EPIDEMIOLOGY AND OUTCOMES OF PATIENTS WITH BRAIN METASTASES FROM COLORECTAL CANCER WHO ARE THESE PATIENTS?

Background: Brain metastases (BM) from colorectal cancer(CRC) are unusual in comparison with other primary sites such as breast and lung. However, an increasing incidence has been reported. The evidence available on the subject is scarce and a better understanding of the disease behavior is warranted. We aimed to characterize the epidemiology and the outcomes of patients (pts) with BM from CRC. Methods: A cohort of pts with BM from CRC was retrospectively evaluated. Pts were treated in a single-center between May-2008 and Apr-2019. BM was confirmed by brain computed tomography or magnetic resonance imaging. Overall survival (OS) was calculated from the time of BM diagnosis to death. Kaplan-Meier method was used to estimate survival. Prognostic factors were evaluated using Cox regression. Results: A total of 247 consecutive pts were evaluated. Median age was 62.9 years (interquartile range [IQR], 53.8 69.6). For most pts (N = 193, 78%), the primary tumor side was the left; 135 (54%) were metastatic at initial presentation; 124 (50%) were male. Only 14 pts (5.6%) had isolated BM; the majority (N = 194, 78%) had at least two extracranial metastatic sites. Ninety-six pts (39%) were RAS wild-type; 68 (27%) RAS mutated; and 83 (34%) were not characterized. Median time from initial diagnosis to BM development was 27.6 months (IQR, 13.1 46.9). BM surgical resection was done for 101 pts (41%) and 140 (57%) received radiation therapy (RT). Median OS was 2.9 months (95% CI, 2.2 3.5). Six-month and 1-year OS rates were 29% (95% CI 23 25) and 13.5% (95% CI 9.2 18.6), respectively. In a multivariable analysis, BM surgical resection (HR 0.49, P < 0.001) and RT (HR 0.48, P < 0.001) were associated with superior OS, while the number of metastatic sites (HR 1.11, P 0.037) was a negative prognostic factor. RAS status was not associated with OS. Conclusions: BM from CRC seem to occur late during disease course and more commonly in pts with a high volume of metastatic disease. A high proportion of primary tumor from the left side was observed. BM from CRC are associated with an extremely poor prognosis. However, selected pts may benefit from BM treatment with surgical resection and RT. A study of molecular features and tumor microenvironment is important for a better comprehension of the disease.