Time trend in the prevalence of intestinal metaplasia in Japan.

In connection with the recently commenced decline of death rate for gastric cancer in Japan, the time trend of intestinal metaplasia of the stomach among the Japanese is investigated. Otherwise normal stomachs from autopsies, and stomachs removed for gastric or duodenal ulcer or for early gastric carcinoma, each collected from two different periods at intervals of 10 to 20 years, are compared histologically. The results show that the prevalence of intestinal metaplasia in those stomachs generally remains high, but that there is a regular downward tendency of the prevalence of confluent intestinal metaplasia in all of those stomachs, except for the stomachs with gastric ulcer. The fall in prevalence is conspicuous among the individuals of middle age groups, especially of patients aged in their 40s, and it is minimized toward old age. The decrease of intestinal metaplasia among the Japanese is considered to have been started only recently. There is no evidence verifying the antecedence of the fall in prevalence of intestinal metaplasia to the decline of death rate for gastric cancer in Japan. Evidence does not suggest a precancerous nature of intestinal metaplasia per se.