Tobacco smoking and esophageal and gastric cardia adenocarcinoma: A meta-analysis

Background: Smoking has been related to esophageal and gastric cardia adenocarcinoma, but the magnitude of the association is uncertain. Methods: We conducted a meta-analysis of 33 studies published up to January 2010. We derived summary estimates using random-effects models. Results: Compared with never-smokers, the pooled relative risk (RR) was 1.76 (95% confidence interval = 1.54-2.01) for ever-smokers, 2.32 (1.96-2.75) for current smokers, and 1.62 (1.40-1.87) for ex-smokers. There was no important difference between esophageal (RR = 1.85 for ever- vs. never-smokers) and gastric cardia (RR = 1.76) adenocarcinoma. We found a direct association with dose (RR = 2.48 [2.14-2.86] for 20 cigarettes/d) and duration (RR = 2.32 [1.92-2.82] for 40 years) of cigarette consumption. Conclusions: This meta-analysis estimates the excess of esophageal and gastric cardia adenocarcinoma risk for smokers. This risk was similar for the 2 cancer sites.