Subsite-specific risk factors for esophageal and gastric adenocarcinoma

Background: The incidence rates of adenocarcinoma involving specific gastric and esophageal subsites are changing significantly, but the risk factors associated with those subsite changes remain controversial. We aimed to describe the site-specific risk factors associated with adenocarcinoma of the stomach and esophagus. Methods: Using the Rochester Epidemiology Project, all cases of gastric and esophageal adenocarcinoma among Olmsted County, Minnesota, residents first diagnosed between 1971 and 2000 were identified. Complete inpatient and outpatient records were reviewed and specific subsites defined. Risk factors were assessed in cases, and age- and sex-matched controls. Results: A total of 186 incident cases of gastric or esophageal adenocarcinoma were identified between 1971 and 2000, in Olmsted County. Gastroesophageal reflux disease (GERD) was a significant risk factor for both esophageal (OR 5.5, 95% CI 1.2-25) and esophagogastric junction adenocarcinoma (OR 13.0, 95% CI 1.7-99), but not for either proximal or distal gastric cancer. Smoking (OR 2.8, 95% CI 1.0-7.8) was associated with distal gastric cancer. Proton pump inhibitor (PPI) exposure was limited and was not a significant risk factor at any subsite. Conclusions: This identification of distinct risk factors by subsite supports the concept that esophageal and gastric adenocarcinomas are two different diseases. Adenocarcinoma of the junction is probably a form of esophageal cancer and should not be coded with gastric neoplasms.