Recent studies have shown that 70-80% of low-grade mucosa-associated lymphoid tissue (
MALT) lymphomas regress in response to eradication of Helicobacter pylori (H. pylori). However, there are no reports on whether gastric high-grade
MALT lymphomas regress after H. pylori eradication. We performed H. pylori eradication
therapy in 4 patients with stage I, high-grade
MALT lymphoma after obtaining their informed consent. H. pylori
infection was observed in all 4 patients. The patients were treated with
proton-pump inhibitor-based eradication
therapy for 1 or 2 weeks, and then underwent endoscopic examination and biopsy sampling. H. pylori eradication was achieved in all 4 patients. Six months after eradication treatment, 2 patients showed complete regression of the
lymphoma and 2 patients showed no change. The 2 patients with non-responding
lymphoma were then treated with an additional
chemotherapy (
CHOP regimen), whereupon the
tumors completely regressed. These patients, followed-up at least 18 months after eradication treatment, showed no recurrence. We also examined genetic alteration of the p53 and K-ras genes and
microsatellite instability in these high-grade
MALT lymphomas. One patient with a
tumor that showed no change after H. pylori eradication, had a loss of heterozygosity of the p53 gene. No other genetic alterations were detected among the patients. Our results indicate that the eradication of H. pylori may be effective not only for patients with low-grade
MALT lymphoma but also for patients with high-grade
MALT lymphoma. The treatment may be efficacious as a first-line
therapy for patients with high-grade
MALT lymphoma. However, our sample size was limited and further studies are needed to clarify the issue.