Does physical activity protect against the development of gastroesophageal reflux disease, Barrett's esophagus, and esophageal adenocarcinoma? A review of the literature with a meta-analysis.

Physical activity affects the functioning of the gastrointestinal system through both local and systemic effects and may play an important role in reducing the risk of esophageal adenocarcinoma. This review assesses the biological mechanisms and epidemiological evidence for the relationship between physical activity and the development of esophageal adenocarcinoma and its precursor diseases: gastroesophageal reflux disease (GORD) and Barrett's esophagus. A search of PubMed, Medline, Embase, and CINAHL was conducted from their inceptions to 25th March 2017 for analytical studies that examined associations between recreational and/or occupational levels of physical activity and the risk of GORD, Barrett's esophagus, and esophageal adenocarcinoma. Where appropriate, a meta-analysis of effects was undertaken. Seven studies were included (2 cohort, 5 case control). For GORD, there were three case-control studies with 10 200 cases among 78 034 participants, with a pooled estimated OR of 0.67 (95% CI 0.57-0.78) for high versus low levels of recreational physical activity. In Barrett's esophagus, there was a single case-control study, which reported no association, OR 1.19 (95% CI 0.82-1.73). For esophageal adenocarcinoma, there were three studies (two prospective cohort, one case control) with 666 cases among 910 376 participants. The largest cohort study reported an inverse association for high versus low levels of recreational physical activity, RR 0.68, 95% CI 0.48-0.96. The remaining two studies reported no associations with either occupational or combined recreational and occupational activity. Heterogeneity in the measurement of exposure (recreational, occupational, and both) made a pooled estimate for esophageal adenocarcinoma inappropriate. Although limited, there is some evidence that higher levels of recreational physical activity may reduce the risk of both GORD and esophageal adenocarcinoma, but further large cohort studies examining the type, intensity and duration of activities that may be beneficial are needed.