Epidemiologic studies of gastric carcinoma: comparison between Iranians and two racial groups in the USA

Gastric carcinoma in 226 cases from the two major racial groups--black and white--in Richmond, VA, USA, and in 75 cases from Shiraz, Iran, were studied. The age at onset and the ratio of intestinal to diffuse gastric carcinoma were compared with those for the high- and low-risk groups from Colombia. Poor socioeconomic conditions are directly related to intestinalization of the gastric mucosa and onset of carcinoma at a relatively young age. In Shiraz, the peak incidence of lymphoma, including intestinal lymphoma, is in the third decade of life; for esophageal carcinoma, it is in the fourth decade, and for gastric carcinoma, in the fifth. Comparison of this age distribution with induction times of neoplasia in immunosuppressed patients supports the suggestion of a common cocarcinogenic factor acting early in infancy. In Richmond, the ratio of intestinal to diffuse carcinoma for the black population is consistently higher than for the white. This difference has increased recently due to a more rapid decline in incidence of intestinal-type gastric carcinoma in the white population than in the black.