Antibiotic Therapy and Antacids in Patients With Malt Lymphoma of the Stomach

OBJECTIVES: I. Evaluate the response of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) to treatment for Helicobacter pylori infection with antibiotics (amoxicillin, clarithromycin, tetracycline, and metronidazole) and with gastric acid inhibitors (omeprazole and bismuth subsalicylate). II. Correlate response with endoscopic tumor grade and clinical and pathological parameters. III. Assess the incidence of H. pylori infection in patients with gastric MALT lymphoma. OUTLINE: All patients are treated on Regimen A; those receiving tetracycline on Regimen A are switched to Regimen B for their second course; those receiving amoxicillin for their first course receive tetracycline for their second course. Regimen A: Antibiotic Therapy with Gastric Acid Inhibition. Amoxicillin (or Tetracycline in penicillin-allergic patients); Clarithromycin; with Bismuth Subsalicylate; Omeprazole. Regimen B: Antibiotic Therapy with Gastric Acid Inhibition. Tetracycline; Metronidazole, METRO, NSC-50364; with Bismuth Subsalicylate; Omeprazole. PROJECTED ACCRUAL: 75 patients will be entered over 3 years.