Radiotherapy for non-gastric intestinal versus gastric MALT lymphoma: a comparison of treatment outcomes

BACKGROUND: Radiotherapy is often used for treating patients with gastric mucosa-associated lymphoid tissue (MALT) lymphomas who fail to respond to Helicobacter pylori eradication. However, non-gastric intestinal MALT lymphoma is rare, and no standard therapeutic strategies have been established. This study was designed to assess the long-term prognosis of non-gastric intestinal MALT lymphoma treated with radiotherapy and to compare the outcomes with that of post-radiotherapy gastric MALT lymphoma. METHODS: The study included 34 patients with stage I EA gastrointestinal MALT lymphoma according to the Ann Arbor classification who underwent definitive radiotherapy. The primary site was the rectum in 3, the duodenum in 1, and the stomach in 30 patients. The radiotherapy dose was 1.5‒2.0 Gy (median, 1.5 Gy) and the total dose was 30‒40 Gy (median, 30 Gy). The clinical target volume (CTV) was defined as the volume of the entire organ with the lymphoma. Adjacent lymph node areas were not routinely included in the CTV. RESULTS: Complete response (CR) was achieved in all patients. There were no local recurrences, and two cases of recurrence were observed at other sites. The 5-year overall survival rates for non-gastric and gastric MALT lymphomas were 100% and 94.7%, respectively, and the 5-year disease-free survival rates were 100% and 95.7%, respectively. None of the patients died of the current illness. CONCLUSION: Radiotherapy for non-gastric intestinal MALT lymphoma is expected to result in good local control and long-term survival, similar to that for gastric MALT lymphoma.