Role of radiotherapy to bulky sites of advanced Hodgkin lymphoma treated with ABVD: Final results of FIL HD0801 trial

The role of consolidation radiotherapy (RT) for bulky lesions is controversial in patients with advanced-stage Hodgkin lymphoma who achieve complete metabolic response (CMR) after doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD)-based chemotherapy. We present the final results of the Fondazione Italiana Linfomi HD0801 trial, which investigated the potential benefit of RT in that setting. In this phase 3 randomized study, patients with a bulky lesion at baseline (a mass with largest diameter ≥ = cm) who have CMR after 2 and 6 ABVD cycles were randomly assigned 1:1 to RT vs observation (OBS) with a primary endpoint of event-free survival (EFS) at 2 years. The sample size was calculated estimating an EFS improvement for RT of 20% (from 60% to 80%). The secondary end point was progression-free survival (PFS). One hundred sixteen patients met the inclusion criteria and were randomly assigned to RT or OBS. Intentionto- treat (ITT) analysis showed a 2-year EFS of 87.8% vs 85.8% for RT vs OBS (hazard ratio [HR], 1.5; 95% confidence interval [CI], 0.6-3.5; P = .34). At 2 years, ITT-PFS was 91.3% vs 85.8% (HR, 1.2; 95% CI, 0.5-3; P = .7). Patients in CMR randomly assigned to OBS had a good outcome, and the primary end point of a 20% benefit in EFS for RT was not met. However, the sample size was underpowered to detect a benefit of 10% or less, keeping open the question of a potential, more limited role of RT in this setting.