A nested case-control study of stomach cancer incidence and serum superoxide dismutase activity in the Japan Collaborative Cohort study in Japan

Background: We conducted a nested case-control study to investigate the association between serum levels of superoxide dismutase (SOD) enzyme and the incidence of stomach cancer. Methods: A nested case-control study was established within the Japan Collaborative Cohort Study. The follow-up period was from 1988 through 1997. Newly diagnosed cases of stomach cancer were recorded in 804 subjects, of these sera were available for 161 cases. Each of these cases was matched on study area, gender and baseline age with two controls; giving 161 stomach cancer cases and 314 control subjects for analysis. Serum levels of SODs were divided into quartiles, with the first quartile used as the reference. Odds ratios (ORs) and 95% confidence interval (95% CI) for the other serum level quartiles were estimated using the conditional logistic model. Results: The adjusted ORs and 95% CI for the second, third, and fourth SOD quartiles were 0.71 (95% CI: 0.42–1.19), 0.59 (95% CI: 0.32–1.10), and 0.86 (95% CI: 0.48–1.54), respectively. Conclusion: We found no association between SOD serum level and the risk of stomach cancer. The role of SOD in the development of stomach cancer requires further investigation.