OBJECTIVES: I. Determine the efficacy and response rate of triple antibiotic therapy for Helicobacter pylori in the healing of lesions in patients with low grade gastric lymphoma. II. Assess the efficacy of chlorambucil in the prevention of relapse in patients after complete eradication of low grade gastric lymphoma. III. Determine the natural history of unresected or partially resected low grade gastric lymphoma treated medically.

OUTLINE: This is a randomized study. Patients are randomized to receive chlorambucil or placebo. Patients receive omeprazole daily for 1 week. Clarithromycin and tinidazole are administered twice daily for 1 week for the eradication of H. pylori infection. Patients are assessed every 2-3 months by endoscopy. Patients may receive a maximum of 3 courses of treatment every 2-3 months. Other regimens may be used if full eradication of H. pylori is not achieved. Patients who achieve complete response (eradication of H. pylori) are randomized to receive oral chlorambucil or placebo daily for 14 days. Treatment is repeated every 28 days for 6 courses. Patients are followed every 6 months for 2 years, then yearly thereafter.

PROJECTED ACCRUAL: A total of 200 patients will be accrued for this study.