Prevalence and prognosis of gastric cancer detected by screening in a large Japanese population: Data from a single institute over 30 years

Background and Aim: In Japan, screening examination with photofluorography is widely performed to reduce the mortality due to gastric cancer. The possibility of a future decline in gastric cancer cases and changes in its characteristics is suggested. The aim of this study was to examine the usefulness of direct radiology as a general health screening technique and the historical changes of gastric cancer in Japan. Methods: This study involved 936 patients with gastric cancer whose carcinomas were detected by direct radiology as part of a general health screening at the Aichi Prefectural Center for Health Care from 1970 to 2000. We studied the prevalence of gastric carcinoma, its prognosis, differences between the two histological types of carcinoma and historical changes. Results: The age-adjusted cancer detection rate slightly decreased. Comparing two histological types, diffuse-type carcinoma cases relatively increased. Intestinal-type carcinomas increased in the lower portion of the stomach, whereas diffuse-type increased in the upper portion. The 5-year survival rate was 92.7% for intestinal-type carcinoma and 84.8% for diffuse-type. Diffuse-type carcinomas were further progressed than intestinal-type when detected by direct radiology; however, detection of diffuse-type improved, so the percentage of early gastric cancer of diffuse type significantly increased, and the survival rate significantly improved, from 70.4% to 90.5%. Conclusion:The prevalence of gastric cancer has been decreasing, but the proportion of diffuse-type carcinoma localized in the upper portion of the stomach has been increasing in Japan.