Consolidative radiation in the management of relapsed/refractory Hodgkin lymphoma: a single institution study

BACKGROUND: 5-30% of Hodgkin Lymphoma (HL) patients are refractory to primary therapy or have disease relapse requiring additional salvage treatment. High-dose chemotherapy with autologous stem cell transplant (ASCT) is the current standard of care for refractory and recurrent HL. The utility of consolidative RT in the peri-transplant setting has been heavily disputed in recent years. The goal of this study is to evaluate the impact of consolidative radiotherapy in the setting of ASCT in patients with relapsed/refractory HL. METHODS: We retrospectively reviewed 179 consecutive patients with HL who underwent salvage chemotherapy followed by high dose chemotherapy and an ASCT for relapsed (63.4%) or refractory (36.6%) disease with or without subsequent consolidative RT from 2000 to 2019 at our institution. RESULTS: Median follow up was 59.4 months. Post-transplant consolidative RT was delivered to 72 patients (40%) at a median dose of 36 Gray (Gy). Nearly two-thirds (46/72, 63.8%) of patients received involved site radiation therapy. Consolidative RT was associated with younger age (median 32 vs. 42 years, p < 0.001), stage I-II disease at the time of salvage chemotherapy (76.4% vs 52.3%, p = 0.001), and no prior RT (76.4% vs 45.8%, p < 0.001). Univariate analysis revealed consolidative RT was associated with an improved 2-year PFS rate (84.1% vs 64.1%, p = 0.005) and OS rate (95.7% vs 80.8%, p = 0.017). In the Cox regression analysis, PFS was associated with consolidative RT (HR: 0.492, 95% CI: 0.288-0.84, p = 0.009) along with ECOG performance status < 2 (HR: 0.188, 95% CI: 0.045-0.79, p = 0.022), complete response to salvage chemotherapy (HR: 0.463, 95% CI: 0.233-0.92, p = 0.028), and stage I-II disease (HR: 0.546, 95% CI: 0.325-0.918, p = 0.022). Similarly, OS was associated with consolidative RT (HR: 0.398, 95% CI: 0.205-0.771, p = 0.006) and ECOG performance status < 2 (HR: 0.073, 95% CI: 0.016-0.333, p = 0.001). Subset analysis suggested that RT was associated with an improved PFS and OS even in those with complete response or non-bulky disease after ASCT. Minimal toxicity was observed in irradiated patients and no deaths were associated with treatment toxicity. CONCLUSIONS: Peri-transplant consolidative RT for the salvage management of HL is an effective, complimentary, and well tolerated addition to ASCT for the treatment of relapsed and refractory HL.