Identification of a shared protective genetic susceptibility locus for colorectal cancer and gastric cancer

Risk of both colorectal cancer (CRC) and gastric cancer (GC) is considered to be heritable with mounting evidence for their genetic susceptibility. However, it remains unknown whether a shared genetic background is underlying these two cancers. A total of ten single nucleotide polymorphisms (SNPs) associated with digestive system cancers risk were selected from previous genome-wide association studies. All SNPs were genotyped in 449 CRC cases, 588 GC cases, and 703 controls using Sequenom Mass-ARRAY technology. Odds ratios (ORs) and 95 % confidence intervals (95 % CIs) were estimated using unconditional logistic regression analysis with adjustment for age and gender, and evaluated their association with both cancers in a Han Chinese population using chi-squared (χ²) test and genetic model analysis. By χ² test, we found that rs2057314 (p = 0.028; OR = 1.21) was significantly associated with an increased risk of CRC, rs7758229 (p = 0.005; OR = 0.77) was significantly associated with a decreased risk of GC. Furthermore, a shared susceptibility locus rs9502893 was found to have significant protective effect against CRC (p = 0.010; OR = 0.80) and GC (p = 0.0003; OR = 0.74). Our findings could provide insight into the underlying shared a partly overlapping genetic aspect of CRC and GC in a Chinese population. Additional studies are required to verify and discover more common genetic variants associated with risk for digestive system cancers.