IMPACT OF RITUXIMAB MAINTENANCE ON SURVIVAL IN PATIENTS WITH MANTLE CELL LYMPHOMA; A POPULATION-BASED COHORT STUDY.

Newly diagnosed mantle cell lymphoma (MCL) is commonly treated with rituximab (R) combined with anthracycline-based chemotherapy, with or without autologous stem-cell transplantation (ASCT). While rituximab maintenance (RM) in clinical trials has been shown to prolong overall survival (OS), its impact at population level remains largely unknown. This study evaluates the effect of RM on outcome of patients with MCL. Patients aged ≥18 years diagnosed with MCL between 1989-2020 were identified using the Netherlands Cancer Registry, and categorized into periods reflecting R and RM implementation (1989-2000, 2001-2014, 2015-2020). Treatment strategies were categorized as R-CHOP, R-CHOP followed by high-dose cytarabine (intensive) and ASCT, and other. The primary endpoint was 5-year OS. Multivariable analysis (MVA) was performed using Cox regression. Among 4,751 patients, 5-year relative survival (RS) improved from 38% (1989-2000) to 47% (2001-2014) and 60% (2015-2020) (p<0.01), irrespective of age (≤65 years: 32% and >65 years: 20% increase over time. Patients with progression (POD) within 12 months had 2-year OS of 25%. Since 2014, RM implementation reached 80% in younger and 50% in older patients. RM was associated with improved OS especially for patients in partial remission (PR), after induction treatment with R-CHOP. In MVA patients with R-CHOP, RM was independently associated with reduced mortality (hazard ratio 0.69; 95% CI, 0.53 - 0.90). Relative survival in MCL improved by more than 20% over the past 30 years. Early disease progression remains associated with poor outcome. RM was associated with improved survival, especially for patients achieving PR following R-CHOP.