Impact of transformation on the survival of patients diagnosed with follicular lymphoma that progressed within 24 months

Background: Progression within 24 months after initiating treatment (POD24) is established as an unfavorable event predicting poor prognosis in patients with follicular lymphoma (FL). However, little is known about the impact of transformation on the outcome of FL patients with POD24 although transformation could be related to early progression and poor prognosis in FL patients. Methods: We investigated the occurrence of transformation and its association with POD24 in FL patients receiving RCVP (rituximab, cyclophosphamide, vincristine and predisone, n = 152), RCHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and predisone, n = 111), and BR (bendamustine, rituximab, n = 61). Results: With the median follow-up of 48.3 months, disease progression occurred in 94 patients (94/324, 29.0%) including 58 POD24 cases (58/324, 17.9%), and POD24 was more frequent in the RCVP (25/152, 16.4%) and RCHOP (28/111, 25.2%) groups than the BR group (5/61, 8.2%). Transformation was documented in 38 cases, including 22 of which were clinically designated as transformation. Among the 58 cases with POD24, the proportion with transformation differed across groups: RCVP (8/25, 32%); RCHOP (16/28, 57.1%); and BR (5/5, 100%). Transformation accounted for 50% (29/58) of POD24 cases whereas only 9 (9/36, 25%) patients had transformation with progression after 24 months. Patients with transformation within 24 months had the worst survival outcome regardless of POD24. Conclusions: Transformation negatively impacted survival among FL patients more than POD24 itself. With caution, our findings suggest that BR may reduce POD24 more than RCVP or RCHOP. However, BR efficacy may not reduce the occurrence of transformation.