Patterns of disease progression and outcomes in a randomized trial testing ABVD alone for patients with limited-stage Hodgkin lymphoma

Background: In the National Cancer Institute of Canada Clinical Trials Group/Eastern Cooperative Oncology Group HD.6 trial, progression-free survival was better in patients randomized to therapy that included radiation, compared to doxorubicin (Adriamycin®), bleomycin, vinblastine and dacarbazine (ABVD) alone. We now evaluate patterns of progression and subsequent outcomes of patients with progression. Patients and methods: After a median of 4.2 years, 33 patients have progressed. Two radiation oncologists determined whether sites of progression were confined within radiation fields. Freedom from second progression (FF2P) and freedom from second progression or death (FF2P/D) were compared. Results: Reviewers agreed for the extended (kappa = 0.87) and involved field (kappa = 1.0) analyses. Progression after ABVD alone was more frequently confined within both the extended (20/23 vs. 3/10; P = 0.002) and involved fields (16/23 vs. 2/10; P = 0.02). There was no difference in FF2P between groups [5-year estimate 99% (radiation) versus 96% (ABVD alone)] [hazard ratio (HR) = 3.14, 95% confidence interval (CI) 0.63–15.6; P = 0.14]; the 5-year estimates of FF2P/D were 94% in each group (HR = 1.04, 95% CI 0.41–2.63; P = 0.93). Conclusion: Treatment that includes radiation reduces the risk of progressive Hodgkin lymphoma in sites that receive this therapy, but we are unable to detect differences in FF2P or FF2P/D.