Retrospective Characterization of Nodal Marginal Zone Lymphoma.

NNodal marginal zone lymphoma (NMZL) is a rare non-Hodgkin B-cell lymphoma that has historically been difficult to define, though is now formally recognized by the World Health Organization Classification. To better characterize the clinical outcomes of patients with NMZL, we reviewed a sequential cohort of 187 patients with NMZL to describe baseline characteristics, survival outcomes, and time-to-event data. Initial management strategies were classified into five categories: observation, radiation, anti-CD20 monoclonal antibody therapy, chemoimmunotherapy, or other. Baseline Follicular Lymphoma International Prognostic Index (FLIPI) scores were calculated to evaluate prognosis. A total of 187 patients were analyzed. Overall 5-year OS was 91% (95% CI 87%-95%), with a median follow-up time among survivors of 71 (range: 8-253) months. A total of 139 patients received active treatment at any point, with a median follow-up time among never-treated survivors of 56 (range: 13-253) months. The probability of remaining untreated at 5-years was 25% (95% CI 19%-33%). For those initially observed, the median time to active treatment was 72 months (95% CI 49-not reached). For those who received at least one active treatment, the cumulative incidence of receiving a second active treatment at 60 months was 37%. Transformation to large B cell lymphoma was rare, with a cumulative incidence of 15% at 10 years. In summary, our series is a large cohort of uniformly-diagnosed NMZL with detailed survival and time to event analyses. We show NMZL commonly presents as an indolent lymphoma for which initial observation is often a reasonable strategy.