Exclusive moderate-dose radiotherapy in gastric marginal zone B-cell MALT lymphoma: Results of a prospective study with a long term follow-up.

Background: In gastric MALT lymphomas persisting after Helicobacter pylori (H. pylori) eradication, a treatment by moderate-dose radiotherapy (RT) has been proposed but its efficacy has not been confirmed in large prospective series with long term endoscopic follow-up.

Method: Patients with localised gastric MALT lymphoma persisting after H. pylori eradication were offered moderate-dose RT (30Gy, 2Gy/fraction) and followed with annual endoscopies. All biopsies before and after RT were reviewed by a committee of pathologists.

Results: From 1995 to 2011, out of the 232 patients followed prospectively, 53 received RT for persistence of lymphoma after H. pylori eradication: either macroscopic ulcer (n=31), or microscopic lymphomatous infiltrate (n=22), after a mean follow-up of 12 and 31months, respectively. All lymphomas were localised (45 stage IE and 8 stage IIE) and 38 (72%) were H. pylori-positive. The mean clinical and endoscopic follow-up from diagnosis was 7.6years (2.2-19.1). No acute or late toxicity occurred. A complete remission was achieved in all patients but one (98%) with no relapse after a median follow-up of 4.9years (1.3-16.6) after completion of RT. Overall survival and 5-year disease specific survival were 94% and 100%, respectively. One patient died of gastric adenocarcinoma.

Conclusion: Moderate-dose RT (30Gy) is effective and safe for localised gastric MALT lymphoma persisting after H. pylori eradication.