Outcome ascertainment—We identified cases of gastric cancer through linkage with the Swedish cancer register, using the seventh version of the international classification of diseases (ICD-7) code 151. In subanalyses, we divided gastric cancer into cancer of the gastric cardia (code 151.1) and non-cardia gastric cancer (except code 151.1). Patients who underwent gastric resection for non-malignant indications during the follow-up were censored on the date of the operation. Gastric resections were ascertained in the patient register. For major upper gastrointestinal surgery, the completeness of the Swedish patient register is deemed to be well over 90%.