Body Mass Index Trajectories, Weight Gain, and Risks of Liver and Biliary Tract Cancers

Background: Little is known about the role of early obesity or weight change during adulthood in the development of liver cancer and biliary tract cancer (BTC). Methods: We investigated the associations of body mass index (BMI) and weight trajectories with the risk of liver cancer and BTC in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. BMI was self-reported at ages 20 years and 50 years and at enrollment. BMI trajectories were determined using latent class growth models. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Results: During a median follow-up of 15.9 years among 138 922 participants, 170 liver cancer and 143 BTC cases were identified. Compared with those whose BMI did not exceed 25 kg/m2, participants with BMI exceeding 25 kg/m2 at age 20 years had increased risks of liver cancer (HR = 2.03, 95% CI = 1.26 to 3.28) and BTC (HR = 1.99, 95% CI = 1.16 to 3.39). Compared with participants maintaining normal BMI until enrollment, trajectory of normal weight at age 20 years to obesity at enrollment was associated with increased risk for liver cancer (HR = 2.50, 95% CI = 1.55 to 4.04) and BTC (HR = 1.83, 95% CI = 1.03 to 3.22). Compared with adults with stable weight (±5 kg) between age 20 years and 50 years, weight gain of 20 kg and greater between ages 20 years and 50 years had higher hazard ratios of 2.24 (95% CI = 1.40 to 3.58) for liver cancer and 1.86 (95% CI = 1.12 to 3.09) for BTC. Conclusions: Being overweight and/or obese at age 20 years and BMI trajectories that result in being overweight and/or obese may increase risk for both liver cancer and BTC.