PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: Not specified Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to the abdomen Surgery: No prior gastric surgery except simple closure of perforated ulcer with or without wedge excision of the ulcer Other: No prior therapy for gastric lymphoma At least 30 days since experimental therapy No other concurrent experimental therapy At least 30 days since antibiotics with activity against H. pylori