Role of diagnostic and therapeutic improvements in the decline of gastric cancer mortality rate in Japan.

The effects of improvements of clinical diagnosis and treatment of gastric cancer on the decline in gastric cancer mortality rate in Niigata Prefecture were evaluated. Analysis of mortality statistics since 1950 and registries of surgical cases with gastric cancer in the 10 years from 1972 provided the following conclusions. (1) The age-adjusted gastric cancer mortality rate (the demography of Japan in 1965 was used for the standard population) began to decline in 1968, and the mean mortality rates were 60.5 per 100,000 population in 1958-1967 and 38.6 in 1981, showing 21.9 decrease in 14 years in Niigata Prefecture. (2) Surgical cases increased from 1,258 to 1,870, and those of early gastric cancer in particular showed a rapid increase from 133 to 421 in 10 years (1972-1981). (3) The age-adjusted early gastric cancer rate in surgical patients increased from 4.6 per 100,000 population to 11.5 within 10 years. Since the 5-year survival rate of patients with early gastric cancer is more than 90%, 30.1% of the decrease in the mortality rate should be attributed to patients with early gastric cancer who are surviving. (4) Improved diagnostic and therapeutic techniques for advanced gastric cancer might account for 16.0% of the decline in the mortality rate. (5) Overall, 46.1% of the decline in the mortality rate can be ascribed to improved diagnostic and therapeutic techniques, and the remaining 53.9% to a decreased incidence of gastric cancer.