Dietary patterns and risk of pancreatic cancer: a systematic review

Context: Pancreatic cancer has the highest case fatality rate of all major cancers. Objective: A systematic review using PRISMA guidelines was conducted to summarize the associations between dietary patterns and risk of pancreatic cancer. Data Sources: PubMed and Web of Science databases were searched for case-control and cohort studies published up to June 15, 2016. Study Selection: Eligible studies included a dietary pattern as exposure and pancreatic cancer incidence or mortality as outcome and reported odds ratios, hazard ratios, or relative risks, along with corresponding 95%CIs. Data Extraction: Important characteristics of each study, along with the dietary assessment instrument, the component foods or nutrients included in each dietary pattern or the scoring algorithm of a priori dietary patterns, were presented. For each dietary pattern identified, the estimate of association and the 95%CI comparing the highest versus the lowest category from the model with the most covariate adjustment were reported. Results: A total of 16 studies were identified. Among the 8 studies that examined data-driven dietary patterns, significant positive associations were found between pancreatic cancer risk and the Animal Products, Starch Rich, and Western dietary patterns, with effect estimates ranging from 1.69 to 2.40. Significant inverse relationships were found between risk of pancreatic cancer and dietary patterns designated as Fruits and Vegetables, Vitamins and Fiber, and Prudent, with effect estimates ranging from 0.51 to 0.55. Eight studies of a priori dietary patterns consistently suggested that improved dietary quality was associated with reduced risk of pancreatic cancer. Conclusions: Better diet quality is associated with reduced risk of pancreatic cancer. The associations between dietary patterns and pancreatic cancer were stronger in case-control studies than in cohort studies and were stronger among men than among women.