Kazutaka Suzuki, Kana Miyazaki, Naoko Asano, Hiroyuki Takahashi, Yusuke Koba, Nobuhiro Hiramoto, Ilseung Choi, Hiroshi Arima, Toshiki Uchida, Nobuhiko Nakamura, Hiro Tatetsu, Hideki Uryu, Shunsuke Ito, Takeharu Kato, Hirokazu Sasaki, Tohru Murayama, Junji Hiraga, Naoki Takahashi, Tetsu Kobayashi, Motoshi Takao, Isao Tawara, Motoko Yamaguchi
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.