Time to Next Treatment Within 24 Months ( TTNT24 ) as a Predictor of Survival in Lymphoplasmacytic Lymphoma/Waldenström Macroglobulinemia: A Population‐Based Observational Study

ABSTRACT Introduction Prognostic models in Waldenström's macroglobulinemia (WM) are typically static, baseline tools applied before treatment initiation and do not account for dynamic post‐treatment factors. We evaluated time to next treatment within 24 months (TTNT24), as a prognostic marker in symptomatic patients, and time to lymphoma treatment within 24 months (TTLT24) in initially observed asymptomatic patients. Methods In this observational cohort study, patients diagnosed with lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM) in Region Zealand from 2000 to 2023 were identified using Danish national registries and health records. TTNT24 was defined as initiation of second‐line treatment within 24 months of first‐line therapy. TTLT24 was defined as lymphoma‐directed treatment initiated within 24 months of diagnosis in initially asymptomatic patients. Results Among 526 LPL/WM patients, 218 symptomatic patients were evaluated for TTNT24 with 33 (15%) patients receiving second‐line treatment within 24 months. TTNT24‐positive patients demonstrated inferior overall and lymphoma‐related survival compared to TTNT24‐negative patients. TTNT24 remained significant in multivariate analysis. Among 310 asymptomatic patients, TTLT24 was significantly associated only with lymphoma‐related survival. Conclusion TTNT24 and TTLT24 may serve as dynamic prognostic markers in real‐world LPL/WM populations. Their relevance in the era of targeted therapies warrants further investigation.