PET-adapted therapy for advanced Hodgkin lymphoma - systematic review.

Introduction: Positron emission tomography-computed tomography (PET-CT) performed after two chemotherapy cycles (PET-2) has become an accepted prognostic tool in Hodgkin lymphoma (HL). We evaluated the effect of PET-adapted strategy on outcome in advanced stage HL.

Methods: In August 2017, we searched electronic databases, conference proceedings and ongoing trials. We included all studies in which treatment modification for advanced HL was performed based on the results of the interim PET scan. The primary analysis included randomized controlled trials (RCTs). Outcomes were progression-free survival (PFS) and overall survival (OS).

Results: We identified 13 studies (4 RCTs, 7 phase II and 2 retrospective studies), conducted between 1999 and 2014, including 6856 patients. Of the four RCTS: one used therapy escalation, one did de-escalation and two trials performed both. Outcomes were assessed at different time point between 2 and 5 years. Three RCTs for de-escalating therapy, obtained similar outcomes despite reducing therapy, with a 2-year PFS of 88-92% (6 escalated BEACOPP (EB) vs. 4 ABVD cycles), a 5-year PFS of 91-92% (6/8 EB vs. 4 EB cycles) and a 5-year PFS of 80-82% (6 ABVD vs. omitting bleomycin after two successful ABVD cycles). Two RCTs implemented escalation. The randomization was between adding rituximab or not. In both trials, it did not affect outcome, with a 4-year PFS of 68-69% (addition of rituximab to BEACOPP after 2 ABVD cycles) and 5-year PFS of 88-90% (addition of rituximab to EB after 2 EB cycles). Performing true randomization between PET-adapted and a standard ABVD control arm was not feasible, given historical data.

Conclusions: This systematic review of PET-adapted therapy, mainly based on RCTs, suggests that a change to the treatment paradigm is appropriate in advanced HL.