Metabolic syndrome and insulin resistance in relation to biliary tract cancer and stone risks: a population-based study in Shanghai, China

Background: Serum lipids, diabetes, and obesity, individual components of metabolic syndrome, are associated with biliary tract cancer and stone risk, but the associations of metabolic syndrome or insulin resistance with biliary tract cancers and stones are not well studied. Methods: In this population-based case-control study in Shanghai, China (627 biliary tract cancers, 1037 biliary stones, and 959 controls), metabolic syndrome was defined as the presence of any three of the five components, including high waist circumference, high triglycerides, low high-density lipoprotein cholesterol (HDL), high blood pressure, and diabetes. Insulin resistance and β -cell function were assessed, using homeostasis assessment models. Results: Metabolic syndrome was significantly associated with gallbladder cancer (odds ratio (OR)=2.75, 95% confidence interval (95% CI)=1.82–4.15) and biliary stones (OR=1.64, 95% CI=1.24–2.16), with a significant dose effect with increasing number of metabolic syndrome components ( P trend