Influence of genetic variants of genes potentially associated with colorectal brain metastases on overall survival.
487 Background: Brain metastases (BM) in colorectal cancer (CRC) are rare, developing in only 0.3-9% of the patients, and considered a late-stage manifestation of the disease. The aim of this study was to investigate whether genetic variants of genes involved in BM-related pathways, such as integrin, invasion- and adhesion-mediating, angiogenic and tumor suppressing pathways, are associated with outcome. Methods: Genomic DNA was extracted from formalin-fixed paraffin embedded resected BM from 70 patients with histologically proven CRC. Single nucleotide polymorphisms (SNP) in seven genes (CXCR4, MMP9, ST6GALNAC5, ITGAV, ITGB1, ITGB3, KLF4) were analyzed by direct Sanger DNA sequencing and evaluated for association with overall survival (OS) from resection of BM. Only SNPs with an allele frequency of ≥ 10% were analyzed. Results: In univariate analysis, rs17577 (MMP9) and rs4642 (ITGB3) showed a significant difference in OS [(G/G 7.4 months, G/A 5.1 months; HR (95% CI) 1.83 (0.95-3.53), p = 0.0440) and (A/A 9.4 months, A/G 4.8 months, G/G 4.3 months; HR (95% CI) 0.81 (0.44-1.49) and 2.14 (0.98-4.67), p = 0.0354), respectively]. In multivariate analysis adjusted for baseline characteristics [primary tumor site (right colon, left colon, rectal), chemotherapy before BM (yes/no), BM location (supratentorial, infratentorial, both), Karnofsky performance status (<80, 80-100)], rs2236599 (KLF4), and rs10171481 (ITGAV) are significant in OS [(G/G 7.4 months, G/A or A/A 4.8 months; HR (95% CI) 3.19 (1.55-6.53), p = 0.0016) and (A/A 5.7 months, A/G 4.4 months, G/G 15.5 months; HR (95% CI) 0.61 (0.29-1.29) and 0.25 (0.10-0.60), p = 0.0082), respectively]. Conclusions: This study suggests for the first time a prognostic effect of the SNPs involved in the BM pathway. Further analyses are needed to confirm these findings.