BACKGROUND To compare clinicopathologic and molecular characteristics of low-grade gastric mucosa-associated lymphoid tissue lymphoma depending on Helicobacter pylori positivity and to find out a predictive factor for unresponsiveness to Helicobacter pylori eradication therapy in Korea.

METHODS A total of 53 Helicobacter pylori-positive and 13 negative mucosa-associated lymphoid tissue lymphoma patients were enrolled, and tissues from 21 patients were investigated to examine the presence of t(11;18)(q21;q21) with fluorescence in situ hybridization. Clinicopathologic features such as the endoscopic appearance, dominant site of lesion, depth of invasion, clinical stage, and the existence of MALT1 gene rearrangement were compared between these two groups. Fifty-six patients who underwent H. pylori eradication therapy were divided into responder and nonresponder groups. The two groups were analyzed to calculate odds ratios for resistance to the eradication.

RESULTS Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue lymphoma patients averaged a more advanced clinical stage than H. pylori-positive (p = .023) patients. The frequency of t(11;18)/API2-MALT1 did not differ between H. pylori-positive (45.5%) and H. pylori-negative cases (55.6%). Thirty-eight of 51 (74.5%) H. pylori-positive patients achieved complete regression after the eradication, while 2 of 5 (40%) H. pylori-negative patients obtained regression. Presence of lesions in both distal and proximal parts of stomach (p = .041) and bearing of t(11;18)(q21;q21) (p = .007) were predictors for nonresponsiveness for H. pylori eradication.

CONCLUSIONS Helicobacter pylori eradication could be performed as a primary therapy regardless of H. pylori status, and assessing t(11;18)/API2-MALT1 would be considered after failure to remission by H. pylori eradication.