Is susceptibility locus for lung cancer in the 15q25 nicotinic acetylcholine receptor gene cluster CHRNA5-A3-B4 associated with risk of gastric cancer?

An association between common variants in the 15q25 nicotinic acetylcholine receptor (nAChR) gene cluster CHRNA5-A3-B4 (responsible for encoding nAChR subunits) and lung cancer risk has recently been reported in both Caucasian and Chinese population. Cigarette smoking is one of the major risk factors for both lung and gastric cancer. Moreover, nAChR plays an important role in cigarette smoke-related lung carcinogenesis as well as gastric cancer. Nevertheless, no study has evaluated the association between CHRNA5-A3-B4 gene cluster variants (rs667282 and rs3743073, two variants modifying lung cancer risk) and risk of gastric cancer. We genotyped these two single nucleotide polymorphisms(SNPs) and analyzed their associations with risk of gastric cancer in a case-control study of 637 gastric cancer patients and 855 healthy individuals matched by age and sex in a Chinese Han population. The differences in genotype distribution of the two SNPs (rs667282, rs3743073) between the cases and controls were not statistically significant (p = 0.468 and p = 0.495, respectively). Overall, we did not observe a significant association of each genotype of the two SNPs with risk of gastric cancer (TT/CT vs. CC: adjusted OR = 1.12,95 % CI = 0.86-1.45; p = 0.401 for rs667282 and GG/TG vs. TT: adjusted OR = 1.13,95 % CI = 0.90-1.43; p = 0.300 for rs3743073).The results of our study indicated that these two SNPs at the 15q25 locus did not modify gastric cancer risk and the reported risk SNP at 15q25 may be specific to lung cancer. Additional larger studies are needed to further confirm our findings.