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 (χ (2)) test and genetic model analysis. By χ (2) 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.
Keywords: Colorectal cancer; Gastric cancer; Single nucleotide polymorphism; Susceptibility.