Radiotherapy for Advanced Hodgkin Lymphoma with Initial Bulk: A Combined Analysis of Two Randomized Trials

Purpose The role of consolidative radiotherapy (RT) in patients with advanced Hodgkin lymphoma (HL) with initial bulk is unclear. GITIL/FIL HD0607 and FIL HD0801, two randomized controlled trials with similar design and methodologies, did not identify a benefit to consolidative RT after a metabolic complete response (CR) to 6 cycles of ABVD. However, their limited sample sizes reduced statistical power to detect a small but clinically meaningful benefit to RT. Materials and Methods In a secondary analysis of these two phase 3 trials, reconstructed patient data were used to compare outcomes for early and complete responders randomized to no RT or RT to the site(s) of initial bulk. Estimates of progression-free survival (PFS) in the intent-to-treat (ITT) and per-protocol (PP) analyses were generated using the combined data and compared between groups using the log-rank test. Results A total of 412 patients were included in the ITT analysis and 373 patients were included in the PP analysis. Median age was 30-32, 42% of patients were stage IIB, and 73% of bulky sites were located in the mediastinum. For the no RT versus RT groups, 5-year ITT PFS estimates were 90.1% versus 90.1% (p=0.81). Five-year PP PFS rates were 90.9% versus 92.9% (p=0.31), respectively. There was no observed difference between no RT and RT groups in subgroups according to size of bulky disease: 5-7 cm (p=0.78), 7-10 cm (p=0.25), and >10 cm (p=0.69). Conclusion In this combined analysis of two randomized phase 3 clinical trials, consolidative RT to initial sites of bulky nodal involvement was not associated with a PFS benefit in patients with advanced HL in metabolic CR after 2 and 6 cycles of ABVD.