Abstract 5750: Reproductive factors and risks of biliary tract cancers and stones: population-based study in Shanghai, China

Abstract

Abstract Biliary tract cancers, encompassing tumors arising from the gallbladder, extrahepatic bile ducts, and ampulla of Vater, are relatively uncommon but highly fatal. Higher parity has been linked to increased risks of gallbladder cancer and gallstones, but the effects of other reproductive factors are less clear. Thus, we examined the association between reproductive factors and the risks of biliary tract cancers and biliary stones among women in a population-based case-control study in Shanghai, China. A total of 361 incident biliary tract cancer cases (269 gallbladder and 92 extrahepatic bile duct), 647 biliary stone cases, and 586 healthy women randomly selected from the population were included. High parity, early age at first birth, and late age at menarche contributed to a higher risk of gallbladder cancer risk, particularly among women with associated biliary stones. Among women with stones, those who had 4 or more children and had their first child before the age of 23 had a 3.3-fold (95% CI 1.06-10.03) risk of gallbladder cancer, while those with menarche at 16 years or later had a 4.0-fold (95% CI 1.19-13.58) risk. Among parous women, breastfeeding was associated with a reduced risk of bile duct cancer (OR=0.40, 95% CI 0.20-0.81). In contrast, menopausal status, age at menopause, duration of menstruation, and oral contraceptive use were not associated with biliary tract cancer risk. No association was found between biliary stones and any of the reproductive factors examined. Our results provide further support for a role of reproductive factors, especially high parity and late age at menarche, in the development of gallbladder cancer among women with biliary stones. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5750.