Risk of histological transformation and therapy-related myelodysplasia/acute myeloid leukaemia in patients receiving radioimmunotherapy for follicular lymphoma.

Abstract

Histological transformation (HT) of follicular lymphoma (FL) to an aggressive lymphoma after chemotherapy remains a key issue. The incidence of HT after radioimmunotherapy (RIT) is unknown. This single institution study analysed the risk of HT in FL after treatment with yttrium-90 ibritumomab tiuxetan in 115 consecutive patients treated during 1987-2012. RIT was administered for progressive FL in 111 (97%) patients and as first-line therapy in the remaining 4. 28% (n=32) had HT, occurring at a median of 60months from diagnosis and 20months after RIT. 48% (12/25) of patients who received fludarabine developed HT. The estimated 10-year risk of HT in the fludarabine and non-fludarabine groups was 67% and 26% respectively (P=0·015). Only prior fludarabine was significantly associated with predicting the risk of HT after RIT. 8% (9/115) of patients developed therapy-related myelodysplastic syndrome/acute myeloid leukaemia (tMDS/AML) at a median of 41·4months (range, 5-89). The estimated 10-year risk of tMDS/AML in non-fludarabine treated patients (n=90) versus fludarabine treated (n=25) was 13% and 29%, respectively. The estimated overall risk of FL undergoing HT at 10years without fludarabine exposure appears similar to patients reported in the literature that have not received RIT. Patients with prior purine-analogue therapy are at significantly higher risk of HT.