Role of Helicobacter pylori in gastric carcinoma

Helicobacter pylori infection has recently been incriminated in the pathogenesis of gastric carcinoma and chronic atrophic gastritis and intestinal metaplasia are considered to be precursors of this condition. Although the incidence of Helicobacter pylori infection in India is high that of gastric carcinoma is low. We, therefore, decided to examine the association between Helicobacter pylori, intestinal metaplasia and gastric carcinoma in a prospective study.

Fifty patients with carcinoma of the stomach and 50 with non-ulcer dyspepsia underwent upper gastro-intestinal endoscopy and had biopsies from the antrum, body and carcinomatous tissue. In 12 cases of gastric carcinoma, tissue was obtained from resected specimens at operation. The types of gastritis, intestinal metaplasia and presence of Helicobacter pylori were assessed by staining with haematoxylin and eosin, periodic acid-Schiff reagent with alcian blue and Warthin-Starry stains.

The incidence of chronic atrophic gastritis, intestinal metaplasia and Helicobacter pylori were 82%, 36% and 38% in patients with carcinoma and 86%, 4% and 68% in those with non-ulcer dyspepsia. Helicobacter pylori positivity was significantly higher (p < 0.05) and intestinal metaplasia significantly lower (p < 0.001) in patients with non-ulcer dyspepsia than in those with carcinoma. Of the 50 cases with carcinoma, 28 were of the intestinal and 22 of the diffuse type. The incidence of chronic atrophic gastritis, intestinal metaplasia and Helicobacter pylori in the intestinal type of carcinoma was 71%, 46% and 39% while in the diffuse type it was 32%, 23% and 36%. The incidence of Helicobacter pylori infection did not differ significantly in the two types of carcinoma.

We have found that although Helicobacter pylori infection and chronic atrophic gastritis are common in Indians, the incidence of intestinal metaplasia is low. Helicobacter pylori infection was equally common in both the intestinal and diffuse type of gastric carcinomas. Our findings, therefore, cast doubt on the role of Helicobacter pylori infection in gastric carcinogenesis.