Barrett's esophagus and its association with hiatal hernia, cigarette smoking and colonic tumors

Abstract

Introduction and Aims Barrett's esophagus (BE) is a premalignant condition to esophageal adenocarcinoma involving metaplasia of the esophageal epithelium. Since BE was first identified and described, it has been closely associated with hiatal hernia. The strength of the relationship has never been quantified, nor has the association, adjusted for confounders such as obesity and reflux, been examined. Male gender, obesity and reflux are well recognized risk factors for BE, however it is less certain what role environmental factors such as cigarette smoking play in the development of the condition. The association of BE with colonic tumors has also been speculated on but not clearly established. The aim of this thesis was to further explore the epidemiology of BE, specifically the relationship between BE and hiatal hernia, cigarette smoking and colonic tumors, through meta-analyses. Methods Three meta-analyses and systematic reviews were conducted, quantifying the relationship between BE and hiatal hernia, cigarette smoking and colonic tumors, respectively. Four electronic databases (Medline, PubMed, Embase, and Current Contents Connect) were searched for observational studies of BE patients. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random effects model for the association BE with hiatal hernia, cigarette smoking and colonic tumors. Results A positive relationship was observed between BE and hiatal hernia, which remained even after adjusting for reflux. Cigarette smoking was associated with an increased risk of BE. This was reflected in subgroup analyses of ever-, current- and former-smokers. BE was also associated with colonic tumors. The relationship was observed with both benign adenomatous tumors as well as with colorectal cancer, though it was stronger for colorectal cancer. Conclusions The association between BE and hiatal hernia is stronger for long segment BE when compared with short segment BE, and it appears to be independent of reflux. BE patients are also more likely to have ever smoked cigarettes. BE is associated with colonic tumors, with the association being stronger with colorectal cancer than with benign lesions.