Makiuchi, T. et al. International Journal of Cancer. Published online: 31 October 2016
Vegetable and fruit consumption may have a protective effect against several types of cancers. However, the effect on biliary cancers is unclear. We investigated the association of vegetable/fruit consumption with the risks of gallbladder cancer (GBC), intrahepatic bile duct cancer (IHBDC) and extrahepatic bile duct cancer (EHBDC) in a population-based prospective cohort study in Japan.
Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using the Cox proportional hazard model, and the exposure level was categorized into quartiles, with the lowest group used as the reference.
A total of 80,371 people aged 45–74 years were enrolled between 1995 and 1999, and followed up for 1,158,632 person-years until 2012, during which 133 GBC, 99 IHBDC, and 161 EHBDC cases were identified.
Increased consumption of total vegetable and fruit was significantly associated with a decreased risk of EHBDC (HR = 0.49; 95% CI: 0.29–0.81 for the highest group; P-trend = 0.005). From the analysis of relevant nutrients, significantly decreased risk of EHBDC was associated with folate and insoluble fiber (HR = 0.48, 0.53; 95% CI: 0.28–0.85, 0.31–0.88 for the highest group; P-trend = 0.010, 0.023; respectively), and a significant trend of decreased EHBDC risk associated with vitamin C was observed (P-trend = 0.029). No decreased risk of GBC and IHBDC was found. Our findings suggest that increased vegetable/fruit consumption may decrease a risk of EHBDC, and folate, vitamin C, and insoluble fiber might be key contributors to the observed protective effect.
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