Proportion and characteristics of Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue lymphoma: A systematic review and meta-analysis.

Background: While Helicobacter pylori (H. pylori) infection is common in patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma, there are still individuals who test negative for it. The proportion and characteristics of these patients remain unclear.

Methods: We conducted a systematic search of the PubMed, Embase, and Cochrane Library databases for relevant articles. Using a random effects model, we performed a meta-analysis to assess the pooled proportion of gastric MALT lymphoma patients with negative H. pylori tests. Additionally, we compared characteristics between gastric MALT lymphoma patients with and without H. pylori infection to examine clinical features in H. pylori-negative cases.

Results: A total of 50 studies involving 6033 patients were included. The overall proportion of gastric MALT lymphoma patients with negative H. pylori tests was 20.5% (95% confidence interval: 17.0%-24.6%). This rate exhibited an increasing trend over the years, particularly in non-Asian countries and in studies published after 2013, as well as in cases with sample sizes exceeding 100 participants, in male individuals, and among those with proximal or multiple lesions, non-superficial type morphology, submucosal invasion, and advanced clinical staging. Compared to H. pylori-positive patients, those who tested negative were more likely to be male, have proximal lesions, exhibit submucosal invasion, and present with an advanced clinical stage.

Conclusions: This study provides comprehensive information on the proportion and characteristics of H. pylori-negative gastric MALT lymphoma cases, highlighting the need for future clinical attention to treatment and surveillance in this patient population.