Objectives: To prospectively assess the influence of body mass index (BMI), tobacco, and alcohol on the occurrence of esophageal, gastric cardia, and non-cardia gastric adenocarcinoma, and to detect any sex differences that could explain the male predominance of these tumors.
Methods: A case-control study nested in the General Practitioner Research Database in the United Kingdom, 1994--2001. Odds ratios (ORs) were calculated with 95% confidence intervals (CI), including multivariate analysis.
Results: During follow-up of 4,340,207 person-years, we identified 287 esophageal adenocarcinomas, 195 gastric cardia adenocarcinomas, 327 gastric non-cardia adenocarcinomas, and 10,000 controls. A positive association was found between overweight (BMI > 25 kg/m(2)) and esophageal adenocarcinoma (OR 1.67, 95% CI 1.22--2.30), and gastric cardia adenocarcinoma (OR 1.46, 95% CI 0.98--2.18), but not non-cardia gastric adenocarcinoma. The association between BMI and esophageal and gastric cardia adenocarcinoma were dose-dependent and seemingly independent of reflux. No strong sex differences were identified. Smokers, particularly females, were at increased risk of all studied adenocarcinomas, while no association with alcohol was found.
Conclusions: Overweight increases risk of esophageal and gastric cardia adenocarcinoma, while tobacco smoking increases risk of esophageal, gastric cardia, and non-cardia gastric adenocarcinoma. The male predominance is not explained by sex differences in risk factor profiles of the studied exposures.