Clinical implications of recent developments in gastric cancer pathology and epidemiology.

Recent developments in the epidemiology of gastric cancer have direct clinical implications: It is important to classify patients as belonging to communities with high or low gastric cancer risk. Most native white Americans are at low risk. American Indians, blacks, and Hispanics, as well as immigrants from Russia, Scandinavia, Japan, and some Latin American countries, are at high risk. In high-risk populations the predominant histologic type of gastric carcinoma is "intestinal" or "expansive" which tends to form discrete masses, predominates in males and older people, and has a relative better prognosis. In low-risk populations the tumors tend to be "diffuse" or "infiltrative," are frequent in females and younger people, and tend to have a worse prognosis. The intestinal type of gastric cancer is probably related to diet, characterized by low fat and animal protein intake, high ingestion of grains and tubercular roots, high salt intake, and low intake of fresh fruits and fresh vegetables. Some foods such as fava beans and Japanese fish are suspected of yielding gastric carcinogens after nitrosation. Populations at high risk in which the intestinal type predominates have a high prevalence of atrophic gastritis and intestinal metaplasia. Some of these precursor lesions reach the precancerous stage of dysplasia. The management of these lesions needs further clinical research. Some gastrectomy techniques facilitate the reflux of bile acids into the stomach where they may react with nitrite to produce mutagens and possibly carcinogens. The risk of "stump-carcinoma" increases with time after gastrectomy. Billroth II operations should be replaced with techniques that minimize duodenal reflux.