Associations between obesity and biliary tract cancers vary by tumor site, sex, age, and race in the Biliary Tract Cancers Pooling Project

Authors

• AL Van Dyke
• B Zhu
• PT Campbell
• KA McGlynn
• J Koshiol

Abstract

Obesity, a rapidly escalating epidemic affecting approximately one-third of U.S. adults, has been associated with gallbladder cancer (GBC). Due to the rarity and high mortality rate for biliary tract cancers (BTCs), which include GBC, intrahepatic bile duct (IHBDC), extrahepatic bile duct (EHBDC), and ampulla of Vater (AVC) cancers, most studies examining these associations have been case-control studies with limited sample size. We investigated the association between obesity and BTCs by site within the Biliary Tract Cancers Pooling Project (BiTCaPP), comprised of 28 cohort studies involving over 2.8 million participants and 3,890 incident BTCs. Using Cox regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for BTCs and obesity as measured by body mass index (BMI), waist circumference, hip circumference, waist to hip ratio, and waist to height ratio adjusting for sex, age at baseline, self-reported race, and cohort. Associations were strongest for GBC and IHBDC with higher risk with increasing degree of obesity [HR (95% CI) for class III obesity vs. normal weight and P-trend for obesity class: 2.69 (1.55-4.40),

Scientific Focus Area: Epidemiology

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