Survival outcomes and prognostic nomogram for primary pulmonary MALT lymphoma and diffuse large B-cell lymphoma: A SEER database study

Primary pulmonary lymphoma is a rare extranodal malignancy, and robust population-based evidence regarding its treatment and outcomes remains limited. This study aimed to compare treatment patterns and survival outcomes between primary pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma and primary pulmonary diffuse large B-cell lymphoma (DLBCL), as well as to develop an individualized prognostic model for pulmonary DLBCL. Patients diagnosed between 2010 and 2022 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM), Kaplan-Meier analysis, and Cox regression were employed to compare survival outcomes and identify prognostic factors. Additionally, a nomogram was constructed and internally validated for DLBCL. Among the 2,343 patients analyzed, 1,427 had MALT lymphoma and 916 had DLBCL. MALT lymphoma was more frequently managed with surgical intervention, while chemotherapy was more commonly utilized for DLBCL. After PSM, 441 matched pairs were analyzed, revealing that MALT lymphoma was significantly associated with better overall survival (OS) and cancer-specific survival (CSS) compared to DLBCL, with median OS of 131 months versus 68 months, respectively (p < 0.001). In patients with DLBCL, age ≥60 years emerged as an independent adverse prognostic factor, whereas surgical intervention and chemotherapy were independently associated with improved OS and CSS. The nomogram demonstrated moderate discrimination and good calibration in predicting 1-, 3-, and 5-year survival. These findings underscore that histological subtype is a critical determinant of prognosis in primary pulmonary lymphoma. The proposed nomogram may facilitate individualized prognostic assessments in pulmonary DLBCL.