Treatment and outcomes of pulmonary mucosa‐associated lymphoid tissue lymphoma: A multicenter analysis of 186 patients

BACKGROUND: Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) with pulmonary involvement is a rare, indolent lymphoma with no standard treatment approaches. METHODS: To clarify patient characteristics, treatment, and prognosis of pulmonary MALT lymphoma in the modern era, a multi-institutional observational study of patients diagnosed between 2013 and 2022 was conducted. A modified Ann Arbor system was used for the analysis. RESULTS: Among 186 eligible patients, 131 (70%) had stage IE/IIE disease, whereas 55 (30%) had stage IV disease. No patient had stage III disease. With a median follow-up of 57 months, the 4-year overall survival (OS) rates for the stage IE, IIE, and IV groups were 96%, 92%, and 90%, respectively. The stage IIE and IV groups had similar progression-free survival (PFS) that was significantly worse than that of the stage IE group (p < .001). In stage IE/IIE patients, no differences were found in OS (p = .89) or PFS (p = .90) among the first-line treatment groups. In stage IV patients, the stomach was the most common synchronous extranodal site of involvement (36%). There were no differences in OS among the first-line treatment groups (p = .64). CONCLUSIONS: The OS of patients with MALT lymphoma with pulmonary involvement was favorable regardless of first-line treatment modality, including watchful waiting. The short PFS in the stage IIE and IV groups indicates that these groups are candidates for therapeutic development.