Early-life body size and risk of developing biliary tract cancers.

BACKGROUND

Childhood body mass index (BMI) trajectories, BMI, height, and birth weight were investigated in relation to biliary tract cancer (BTC) risk in this population-based cohort study.

METHODS

The study included 172,113 males and 168,503 females born between 1930 and 1996 from the Copenhagen School Health Records Register. Heights and weights measured at ages 6-15 years identified five sex-specific BMI trajectories. BMI and height were analyzed as z scores; overweight was defined via US Centers for Disease Control and Prevention criteria. Sex-specific hazard ratios (HRs) were estimated via birth cohort-stratified Cox regressions.

RESULTS

During a median follow-up of 34.5 years, 635 individuals developed BTCs. Overweight (HR, 1.58; 95% confidence interval [CI], 1.06-2.34) and obesity trajectories in males (HR, 3.22; 95% CI, 1.61-6.44) and the obesity trajectory in females (HR, 2.88; 95% CI, 1.62-5.15) were associated with increased BTC risk compared with the average BMI trajectory. Childhood overweight at age 7 years was associated with increased intrahepatic bile duct cancer risk in males (HR, 2.66; 95% CI, 1.48-4.75) and extrahepatic bile duct cancer risk in females (HR, 3.83; 95% CI, 1.94-7.56). Taller childhood height was linked to a higher BTC risk in males only; birth weight showed no associations.

CONCLUSIONS

Childhood overweight and obesity increase BTC risk in adulthood.