Genetic variants associated with colorectal brain metastases susceptibility and survival.

Colorectal brain metastases (BM) are rare (1-2%) and a late-stage disease manifestation. Molecular mechanisms for BM development are not well understood. We tested whether variants within genes involved in overcoming the blood-brain barrier (BBB) are associated with BM susceptibility and survival in patients with BM. Germline single-nucleotide polymorphisms (SNPs, n=17) in seven genes (CXCR4, MMP9, ST6GALNAC5, ITGAV, ITGB1, ITGB3, KLF4) were analyzed from germline DNA in patients with resected BM (n=70) or no clinical evidence of BM after at least 24 months from diagnosis (control group, n=45). SNPs were evaluated for association with BM susceptibility and overall survival (OS) from BM diagnosis. ST6GALNAC5 rs17368584 and ITGB3 rs3809865 were significantly associated with BM susceptibility. In multivariable analysis adjusted for patient characteristics, KLF4 rs2236599, ITGAV rs10171481, ST6GALNAC5 rs1883778, CXCR4 rs2680880 and ITGB3 rs5918 were significant for OS. This study shows for the first time that variants within genes involved in breaching the BBB are associated with BM susceptibility and survival. These findings warrant further validation to develop better screening guidelines and to identify novel therapy targets for patients with BM.