Outcome of transformed follicular lymphoma worsens according to the timing of transformation and to the number of previous therapies. A retrospective multicenter study on behalf of Fondazione Italiana Linfomi (FIL)

Summary Optimal treatment for transformed follicular lymphoma ( tFL ) is not fully defined. Clinical characteristics and treatments that impact on post‐transformation outcome of 176 biopsy‐proven tFL were analysed. Transformation occurred at initial diagnosis in 52% (Group 1) and after a FL diagnosis in 48% (Group 2). Five‐year overall survival was 84% for Group 1 and 51% for Group 2 ( P < 0·001). In Group 1, 5‐year progression‐free survival was superior after rituximab maintenance compared to observation only (94% vs. 53%, P = 0·024). In Group 2, an inverse trend was found between survival and both a higher number of pre‐transformation treatment lines and a short time‐to‐transformation.