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.