Cholesterol metabolism gene polymorphisms and the risk of biliary tract cancers and stones: a population-based case-control study in Shanghai, China.

Biliary tract cancers are rare but fatal malignancies, with increasing incidence in Shanghai, China. Gallstones, the primary risk factor for biliary tract cancer, typically result from oversaturation of cholesterol in bile. We examined the association of five variants in three lipid metabolism-related genes (CETP, ABCG8 and LRPAP1) and biliary tract cancers and stones in a population-based case-control study in Shanghai, China. We included 439 biliary tract cancer cases (253 gallbladder, 133 extrahepatic bile duct and 53 ampulla of Vater cancer cases), 429 biliary stone cases and 447 population controls. Carriers of the CG genotype of ABCG8 rs11887534 had higher risk of biliary stones [odds ratio (OR) = 2.3, 95% confidence interval (CI) 0.82-6.5), gallbladder cancer (OR = 4.3, 95% CI 1.7-10.4) and bile duct cancer (OR = 1.94, 95% CI 0.64-5.91), compared with carriers of the GG genotype. Analysis stratified by gender showed both male and female carriers of CG rs11887534 had higher risks of biliary stones and gallbladder cancer, although the association was statistically significant only for women and gallbladder cancer (OR = 6.3, 95% CI 1.86-22.3). Carriers of the ABCG8 haplotype C-C (rs4148217-rs11887534) had a 4.16-fold (95% CI 1.71-10.1) risk of gallbladder cancer compared with those carrying the C-G haplotype. Our findings suggest that ABCG8 rs11887534, identified as a gallstone risk single-nucleotide polymorphism by whole genome scan, is also associated with an increased risk of biliary tract cancer.