Folate intake and the risk of upper gastrointestinal cancers: a systematic review and meta-analysis.
OBJECTIVE
There is conflicting evidence on the association between folate intake and the risk of upper gastrointestinal tract cancers. In order to further elucidate this relationship, we performed a systematic review and quantitative meta-analysis of folate intake and the risk of esophageal, gastric, and pancreatic cancer.


METHODS
Four electronic databases (Medline, PubMed, Embase, and Current Contents Connect) were searched to July 26, 2013, with no language restrictions for observational studies that measured folate intake and the risk of esophageal cancer, gastric cancer, or pancreatic cancer. Pooled odds ratios and 95% confidence intervals were calculated using a random effects model.


RESULTS
The meta-analysis of dietary folate and esophageal cancer risk comprising of nine retrospective studies showed a decreased risk of esophageal cancer (odds ratio [OR] 0.59; 95% confidence interval [95% CI] 0.51-0.69). The meta-analysis of dietary folate and gastric cancer risk comprising of 16 studies showed no association (OR 0.94; 95% CI 0.78-1.14). The meta-analysis of dietary folate and pancreatic cancer risk comprising of eight studies showed a decreased risk of pancreatic cancer (OR 0.66; 95% CI 0.49-0.89).


CONCLUSIONS
Dietary folate intake is associated with a decreased risk of esophageal and pancreatic cancer, but not gastric cancer. Interpretation of these relationships is complicated by significant heterogeneity between studies when pooled, and by small numbers of studies available to analyze when stratification is performed to reduce heterogeneity.
The Whiteley-Martin Research Centre, The Discipline of Surgery, University of Sydney, Sydney Medical School, Nepean Hospital, Penrith, New South Wales, Australia.
Martin
M
Tio
Juliana
J
Andrici
Michael R
MR
Cox
Guy D
GD
Eslick
D004938:Esophageal Neoplasms / Q000517:prevention & control*; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D010190:Pancreatic Neoplasms / Q000517:prevention & control*; D039781:PubMed; D012306:Risk
D005492:Folic Acid
esophageal cancer; folate; folic acid; gastric cancer; pancreatic cancer