Hematopoietic cancer and peptic ulcer: a multicenter case-control study

Helicobacter pylori has been suggested as a cause of gastric carcinoma and gastric non-Hodgkin's lymphoma (NHL), In a previous cohort study, a relativ e risk of six for gastric NHL was reported among subjects who tested positi ve for anti-H,pylori antibodies, The association between peptic ulcer and N HL has been studied in a population-based case-control investigation on hem ato-lymphopoietic malignancies in Italy, based on face-to-face interviews t o 2671 cases and 1718 controls (refusal rates 10 and 19%, respectively). Su bjects who reported a diagnosis of peptic ulcer had a relative risk of 5.6 [95% confidence interval (CI) 3.8-8.0] for gastric NHL, whereas the estimat e for nongastric NHL was 1.3 (1.0-1.6). The association with recent diagnos is of ulcer was stronger, but the odds ratio (OR) was as high as 2.1 (95% C I 1.1-4.2) after greater than or equal to 20 years since such diagnosis. Af ter exclusion of the last 2 years before the diagnosis of NHL, and of ulcer s diagnosed before 1978 (when gastroscopy became common in Italy), the OR w as still 5.3 (95% CI 3.0-9.2). We found a strong effect modification by edu cational level, with ORs for ulcer more elevated in higher social groups. G ender was an effect modifier (OR = 4.1 in males, 9.2 in females; P = 0.03 f or heterogeneity), The association with other gastrointestinal pathologies was much lower and statistically not significant. Almost all gastric lympho mas were B-cell NHLs of intermediate grade according to the working formula tion; the majority belonged to the mucosa-associated lymphoid tissue (MALT) type. The association with ulcer was much stronger among MALT lymphomas, b ut only for recent ulcer diagnoses (2-10 years). Our study shows an increas ed risk for gastric NHL, very similar to the estimate reported in a previou s cohort study. The risk was higher among more educated subjects.