Helicobacter pylori and histopathological changes of gastric mucosa in Uganda population with varying prevalence of stomach cancer.

OBJECTIVES Study the pathological changes in gastric mucosa of Nyarwanda, Nkole (both with high prevalence of stomach cancer) and Ganda (with low prevalence of this cancer) ethnic groups in the presence of Helicobacter pylori (H. pylori) infection. RESEARCH QUESTION Do pathological changes accompanying H. pylori infection explain the varying prevalence of stomach cancer in these populations? DESIGN Retrospective cross sectional study. SUBJECTS A total of 114 patients of the above ethnic groups with upper gastrointestinal symptoms who underwent endoscopic biopsy examination between January 1996 and June 2002 formed the basis of this study. RESULTS The severity of gastritis correlated with the presence of H. Pylori in Ganda and Nyarwanda but not in Nkole. Intestinal metaplasia (IM) was observed in Nyarwanda and Nkole and in some of these cases there was H. pylori. Gastric atrophy (GA) was also commonly observed in Nkole and Nyarwanda and H. pylori was detected more in the severe form of GA. Lymphoid follicle formation was not associated with H. pylori infection in all study groups. CONCLUSION The major histological features relating stomach cancer to H. pylori in this study were presence of the infection in IM and GA that was observed mainly in Nyarwanda and Nkole. The lack of association between presence of lymphoid follicle and H. pylori infection probably explains the rarity of MALT lymphoma in Africa as these tumours are said to arise from H. pylori associated lymphoid follicles.