Whether diet influences the risk of biliary tract cancer (BTC) is unknown. We examined the associations of two healthy dietary patterns, including a modified Dietary Approach�to Stop Hypertension (mDASH) diet and a modified Mediterranean (mMED) diet, with the incidence of BTC in a population-based prospective study.

The study population comprised 76,014 Swedish adults who were 45–83 years of age and cancer-free at baseline. The mDASH and mMED diets were calculated from self-reported dietary data collected by a validated food-frequency questionnaire. Cox proportional hazards regression models were used to estimate hazard ratios (HR) with 95% confidence intervals (CI) adjusted for potential confounders.

Over 1,010,777 person-years (mean 13.3 years) of follow-up, 140 extrahepatic BTC cases (including 77 gallbladder cancers) and 23 intrahepatic BTC cases were ascertained by linkage with the Swedish Cancer Register. Adherence to the mDASH and mMED diets was statistically significantly inversely associated with risk of extrahepatic BTC (P_trend�≤�0.0003) and gallbladder cancer (P_trend�≤�0.005) but not intrahepatic BTC (P_trend�≥�0.11). The multivariable HRs (95% CI) for the highest versus lowest tertile of the mDASH diet were 0.41 (0.26–0.64) for extrahepatic BTC and 0.36 (0.20–0.64) for gallbladder cancer. The corresponding HRs (95% CI) for the mMED diet were respectively 0.41 (0.25–0.67) and 0.42 (0.23–0.79).

Adherence to a healthy diet may play a role in reducing the risk of extrahepatic BTC.