Management of gastric mucosa-associated lymphoid tissue lymphoma in patients with extra copies of the MALT1 gene

AIM To identify the clinical features of gastric mucosa-associated lymphoid tissue (MALT) lymphoma with extra copies of MALT1. METHODS This is a multi-centered, retrospective study. We reviewed 146 patients with MALT lymphoma in the stomach who underwent fluorescence in situ hybridization analysis for t(11; 18) translocation. Patients were subdivided into patients without t(11; 18) translocation or extra copies of MALT1 (Group A, n = 88), patients with t(11; 18) translocation (Group B, n = 27), and patients with extra copies of MALT1 (Group C, n = 31). The clinical background, treatment, and outcomes of each group were investigated. RESULTS Groups A and C showed slight female predominance, whereas Group B showed slight male predominance. Mean ages and clinical stages at lymphoma diagnosis were not different between groups. Complete response was obtained in 61 patients in Group A (69.3%), 22 in Group B (81.5%), and 21 in Group C (67.7%). Helicobacter pylori (H. pylori) eradication alone resulted in complete remission in 44 patients in Group A and 13 in Group C. In Group B, 14 patients underwent radiotherapy alone, which resulted in lymphoma disappearance. Although the difference was not statistically significant, event-free survival in Group C tended to be inferior to that in Group A (p = 0.10). CONCLUSION Patients with t(11; 18) translocation should be treated differently from others. Patients with extra copies of MALT1 could be initially treated with H. pylori eradication, similar to patients without t(11; 18) translocation or extra copies of MALT1.