Whole Grain Intake Reduces Pancreatic Cancer Risk: A Meta-Analysis of Observational Studies

Mounting evidence from epidemiology studies suggests that whole grain intake may reduce pancreatic cancer risk, but convincing evidence is scarce. We conducted a meta-analysis to assess the association between whole grain intake and pancreatic cancer risk. Relevant observational studies were identified by searching PubMed, Embase, Scopus, and Cochrane library databases for the period from January 1980 to July 2015, with no restrictions. We calculated the summary odds ratios (ORs) for pancreatic cancer using random-effects model meta-analysis. Between-study heterogeneity was analyzed using the I statistic. A total of 8 studies regarding whole grain intake were included in the meta-analysis. The pooled OR of pancreatic cancer for those with high versus low whole grain intake was 0.76 (95% confidence interval [CI], 0.64-0.91; P = 0.002). There was no significant heterogeneity across these studies (I² = 11.7%; Pheterogeneity = 0.339). In the subgroup analysis by geographic area, the summary ORs of developing pancreatic cancer were 0.64 (95% CI, 0.53-0.79; P < 0.001; I ²= 0%; Pheterogeneity = 0.482) in the United States (n = 4) and 0.95 (95% CI, 0.63-1.43; P = 0.803; I ²= 45.6%; Pheterogeneity = 0.175) in Europe (n = 2). In the subgroup analysis by type of whole grain, the summary ORs were 0.72 (95% CI, 0.60-0.87; P = .001; I² = 0; Pheterogeneity = 0.876) for grains (n = 4) and 0.74 (95% CI, 0.27-2.02; P = 0.554; I² = 86.3%; Pheterogeneity = 0.007) for wheat (n = 2). A high intake of whole grains was associated with a reduced risk of pancreatic cancer. Because of the absent of more cohort studies, further prospective studies need to be conducted to ensure conclusions that are more robust.