CD20 Antibody–Based Combination Therapy May Reduces the Adverse Prognostic Impact of M-Protein Positivity in Marginal Zone Lymphoma

Background Monoclonal M-protein is frequently detected in marginal zone lymphoma (MZL) and has been historically associated with adverse clinical features. Its prognostic value in the era of modern immunotherapy remains unclear. Patients and Methods We retrospectively analyzed 43 patients with MZL, comparing clinical characteristics, treatments, and outcomes between patients with and without M-protein. Progression-free survival (PFS) and overall survival (OS) were assessed using Kaplan–Meier analysis, and prognostic factors were evaluated by Cox regression. Results M-protein was detected in 39.5% of patients and was associated with higher tumor burden, worse performance status, and elevated inflammatory and biochemical markers. However, no significant differences in PFS or OS were observed between groups, and M-protein was not an independent prognostic factor. Most patients received contemporary CD20 antibody–based combination therapies. Conclusion In the setting of modern treatments, M-protein positivity may not confer an adverse prognostic impact in MZL.