Risk of esophageal cancer in diabetes mellitus: a meta-analysis of observational studies.

Objective: Inconsistent findings from observational studies have prolonged the controversy over the effects of history of diabetes mellitus (DM) on the risk of esophageal cancer (EC). We conducted a meta-analysis of epidemiologic studies to evaluate the association of a history of DM with the risk of EC.

Methods: We identified studies by a literature search of MEDLINE (from 1 January 1966) and EMBASE (from 1 January 1974), through 28 Feburary 2011, and by searching the reference lists of pertinent articles. Summary relative risks (SRRs) with 95% confidence intervals (CIs) were calculated with a random-effects model. All statistical tests were two-sided.

Results: A total of 17 studies (6 case-control studies and 11 cohort studies) fulfilled the inclusion and exclusion criteria. Compared with non-diabetic individuals, diabetic individuals had a modestly increased risk of EC (SRRs 1.30, 95% CI: 1.12-1.50), with significant heterogeneity among studies (p = 0.042). In stratified analysis, the SRRs of EC were 1.28 (1.10-1.49) for diabetic men and 1.07 (95% CI, 0.71-1.62) for diabetic women, respectively. In addition, DM was associated with an increased risk of esophageal adenocarcinoma (SRR 2.12, 95% CI 1.01-4.46). There was no significant publication bias (p = 0.127 for Begg's adjusted rank correlation test and p = 0.629 for Egger's regression test).

Conclusion: These findings support the hypothesis that men with diabetes may have a modestly increased risk of EC, while diabetic women were not the case.