IBCL-294: Analysis of follicular lymphoma patients transforming to diffuse large B-Cell lymphoma: A single-center experience

Abstract

Background: Follicular lymphoma (FL) is an indolent B-cell non-Hodgkin lymphoma with a well-recognized risk of histological transformation to diffuse large B-cell lymphoma (DLBCL), which is associated with more aggressive disease and poorer outcomes. This study aimed to access the outcome of transformation to DLBCL from FL in a retrospective analysis. Methods: We conducted a retrospective cohort study of patients diagnosed with FL at a tertiary care center between January 2012 and December 2023. Patients with biopsy-proven transformation to DLBCL were included. Clinicopathological characteristics and survival outcomes were analyzed. Results: Out of 107 patients diagnosed with FL with median follow-up of 60 months, 11 (10%) developed histologic transformation to DLBCL. The median age at FL diagnosis was 56 years, with a median time of 17 months from FL diagnosis to transformation. Transformation was often heralded by rapidly progressive lymphadenopathy, B symptoms, and elevated serum lactate dehydrogenase. All transformed patients received immunochemotherapy, most commonly R-CHOP. The median overall survival following transformation was 40 months. High FLIPI 1 score at baseline was associated with worse post-transformation survival. Five-year survival was significantly worse for patients with vs without transformation (81%, 95% CI 60–100 vs 93%, 95% CI 89–99). At last follow-up, six patients were alive and in remission, while five had died of disease progression or related complications. Conclusions: In this single-center cohort, approximately 10% of FL patients experienced transformation to DLBCL, predominantly within the first 2 years post-diagnosis. Despite standard immunochemotherapy, survival after transformation remained suboptimal.