Primary Colorectal Tumor Location and Predictors for Metastasis to the Brain.

Introduction Although rectal cancer is thought to have a higher rate of metastasis to the brain compared with colon cancer, there is limited and contradictory data on the subject. This study aims to determine the prevalence of brain metastasis for colon and rectal cancers (CRC), and to explore associations and predictors of brain metastasis (BM). Methods The 2010-2016 National Cancer Database (NCDB) was queried for patients with stage IV CRC. Patients with missing data on site of metastasis and primary tumor location were excluded. Chi-square test was used for categorical data and multivariate logistic regression analysis was performed to evaluate the predictors of BM. Results Of 108,540 stage IV CRC patients, the prevalence of BM was 1.21% from the right colon, 1.29% from the left colon, and 1.59% from the rectal adenocarcinoma (p<0.001). The presence of lung, bone, and liver metastases were the strongest predictors for BM. Bone and lung metastases increased the odds for BM by 3.87 (95% CI: 3.36-4.46) and 3.38 (95% CI: 3.01-3.80), respectively while the presence of liver metastasis decreased odds for BM by 55% (OR: 0.45; 95% CI: 0.40-0.50). On multivariate analysis, primary tumor location was not predictive of BM. Discussion This study helps to characterize the prevalence and associations of BM from CRC using the NCDB. The correlation between BM and bone and lung metastases, along with negative association of liver metastasis further supports the hypothesis of systemic transmission of tumor cells. Further identification of predictors and correlations with BM may help guide surveillance among patients with advanced CRC.