Purpose: This study analyzed the outcomes of nonrandomized consolidation radiotherapy (RT) given after chemotherapy in the initial treatment of advanced Hodgkin's lymphoma (HL). The results were collected prospectively within a randomized controlled trial of induction chemotherapy.
Patients and methods: Patients were randomly assigned between doxorubicin, bleomycin, vinblastine, and dacarbazine and one of two prespecified multidrug regimens. At least six cycles of chemotherapy were planned, with up to eight for patients showing slower response. Involved-field RT was recommended for incomplete response to chemotherapy or bulk disease at presentation. The primary outcome measure was progression-free survival (PFS), landmarked from the end of chemotherapy.
Results: Among 807 patients randomly assigned, 702 achieved objective response. Postchemotherapy RT for consolidation was reported in 300 (43%). With median follow-up of 6.9 years, 161 PFS events and 83 deaths were reported. Baseline characteristics showed more patients with bulk disease having RT (190 [63%] v 111 [28%]) and only partial response after chemotherapy (150 [50%] v 36 [9%]). Other baseline characteristics were similar. PFS was superior for patients having RT (hazard ratio [HR], 0.43; 95% CI, 0.30 to 0.60) with 5-year PFS 71% without RT, 86% with RT. A similar advantage was seen for overall survival (HR, 0.47; 95% CI, 0.29 to 0.77). There was no evidence of heterogeneity of treatment effect across subgroups.
Conclusion: Patients who received consolidation RT apparently had better outcomes, consistently across all prognostic groups which persisted in multivariate analysis. This suggests that RT contributes significantly to the cure rate for advanced HL, although patient selection for combined modality treatment requires better definition in prospective trials.