Iwamuro M, et al. - This study aims to classify the clinical features of gastric mucosa-associated lymphoid tissue (MALT) lymphoma with extra copies of MALT1. In comparison to other patients, patients with t(11;18) translocation should be treated differently. Patients with extra copies of MALT1 can be initially treated with H. pylori eradication, comparable to patients without t(11;18) translocation or extra copies of MALT1.