Aspirin and risk for gastric cancer: a population-based case-control study in Sweden.

While aspirin and other non-steroid anti-inflammatory drugs (NSAIDs) are associated with gastric mucosal damage, they might reduce the risk for gastric cancer. In a population-based case-control study in 5 Swedish counties, we interviewed 567 incident cases of gastric cancer and 1165 controls about their use of pain relievers. The cases were uniformly classified to subsite (cardia/non-cardia) and histological type and information collected on other known risk factors for gastric cancer. Helicobacter pylori serology was tested in a subset of 542 individuals. Users of aspirin had a moderately reduced risk of gastric cancer compared to never users; odds ratio (OR) adjusted for age, gender and socioeconomic status was 0.7 (95% CI = 0.6-1.0). Gastric cancer risk fell with increasing frequency of aspirin use (P for trend = 0.02). The risk reduction was apparent for both cardia and non-cardia tumours but was uncertain for the diffuse histologic type. No clear association was observed between gastric cancer risk and non-aspirin NSAIDs or other studied pain relievers. Our finding lends support to the hypothesis that use of aspirin reduces the risk for gastric cancer.