Bone marrow involvement is not associated with the clinical outcomes of gastric mucosa-associated lymphoid tissue lymphoma

Objective Bone marrow (BM) examination is recommended as part of the initial staging work-up in patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma. However, the clinical significance of BM involvement in gastric MALT lymphoma patients has not been evaluated. Materials and methods From November 1995 to September 2014, 496 subjects who were diagnosed with gastric MALT lymphoma and underwent BM examination were eligible to be included in this study. BM involvement was found in 33 patients (6.7%) by retrospective review, and after exclusions, the clinical outcomes of 28 patients with BM involvement and 412 patients without BM involvement were evaluated. Results When comparing the characteristics of patients, age (median 60 vs. 53 years, p = 0.007) and Helicobacter pylori infection rate (71.0% vs. 85.5%, p = 0.040) were different between patients with and without BM involvement, while the location, macroscopic findings, and depth of invasion were similar. The overall complete remission (CR) rate was 85.2% during a median follow-up period of 42 months (interquartile range, 23–66 months) and did not differ between the two groups (78.6 and 85.7%, p = 0.280). Eradication therapy was performed as the first-line treatment in 18 of the 28 patients (64.3%) with BM involvement, and CR was achieved in 13 patients (72.2%). Logistic regression analysis showed that age and location in the upper part of the stomach were factors related to remission failure. Conclusion Gastric MALT lymphoma has a favorable outcome, and eradication therapy can be justified in selected cases even with BM involvement, when these patients are closely monitored.