Helicobacter pylori infection and the risk of gastric carcinoma

Gastric carcinoma (stomach cancer) is the second most common cancer worldwide: although its incidence is declining in the US and western Europe, it is still very common in Latin America and Asia. Infection with Helicobacter pylori, formerly called Campylobacter pylori, is associated with gastric carcinoma. Studies have indicated that H. pylori is particularly related with the intestinal type of adenocarcinoma; the other is the diffuse type. The availability of a blood test for H. pylori makes it possible to diagnose the infection noninvasively. This test was used in a case-control study at a large health maintenance organization to determine the risks for gastric carcinoma. Blood samples collected in the 1960s from 186 patients who developed gastric carcinoma (cases) were analyzed for H. pylori antibodies. Blood samples from the same number of patients without the disease (controls) were also analyzed. Controls were matched with regard to sex, race, age at serum donation, date of donation, and site where the donation occurred. Analysis of tissue biopsy specimens from most of the cases was also carried out. Results showed that infection with H. pylori was a risk factor for gastric adenocarcinoma, both the intestinal and diffuse types. Eighty-four percent of 109 patients with this disease were infected with H. pylori, compared with 61 percent of the controls, yielding a threefold-elevated risk for those who were infected. H. pylori infection was a particularly important risk factor for gastric adenocarcinoma in women (18-fold elevated risk compared with controls) and blacks (9-fold elevation). Peptic ulcer disease was negatively associated with stomach cancer. Smoking and blood group did not appear to be factors in developing the disease. however, a history of stomach surgery was a risk factor for stomach cancer. Although it is possible that vulnerability to H. pylori and cancer are caused by a third factor, this is unlikely. The physiological reasons for this are enumerated. H. pylori infection can not be considered the sole explanation for stomach cancer, since it is very common. A reasonable estimate of its role in gastric carcinoma is that it causes 60 percent of the disease worldwide. (Consumer Summary produced by Reliance Medical Information, Inc.)