Evaluation of a screening program on reduction of gastric cancer mortalityin Japan: Preliminary results from a cohort study

Background. Systematic population-based screening for gastric cancer is wid ely spread in Japan. However, the case-control study method has been the ma in method used to evaluate the effectiveness of the screening to reduce gas tric cancer mortality in Japan. Methods. This article presents a population-based cohort study. A questionn aire about lifestyles and dietary habits was distributed to 36,990 resident s in a city of Japan. The response rate to the questionnaire was 92.0%. Aft er ineligible responders had been excluded, 24,134 subjects were classified into screened and unscreened groups according to their self-reports of par ticipation in the screening the previous year. We followed them up for 40 m onths and linked resident death records in the city. We compared mortality from gastric cancer and all other causes between the groups by using the Co x proportional hazard model. Results. The follow-up period was 78,156.6 person-years from September 1992 to December 1995. The multivariate relative risks for gastric cancer death of the screened group in comparison with the unscreened group were 0.72 (9 5% CI 0.31-1.66) among males and 1.46 (95% CI 0.43-4.90) among females. Conclusion. Although our data are preliminary, we were unable to demonstrat e a large contribution of the present screening program to decreasing gastr ic cancer mortality. Further follow-up is needed to increase the precision. (C) 1999 American Health Foundation and Academic Press.