Favorable outcomes with de-escalated radiation therapy for limited-stage nodular lymphocyte-predominant Hodgkin lymphoma

Radiation fields for limited-stage nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) have shrunk over time; involved-site radiation therapy (ISRT) has replaced extended-field radiation therapy (EFRT) and involved-field radiation therapy (IFRT), but this has not been validated. The role of systemic therapy is unclear. We reviewed 71 stage I/II NLPHL patients and assessed progression-free survival (PFS), overall survival (OS), locoregional disease-free survival, and distant disease-free survival (DDFS). Median patient age was 39 years, and 61% had stage II disease. Thirty-six (51%) received radiation therapy (RT) only, 6 (8%) received systemic therapy only, and 29 (41%) received both. More patients receiving combined therapy had B symptoms (P = .035) and stage II disease (P = .001). In the RT-only group, 9 (25%) received EFRT, 13 (36%) received IFRT, and 14 (39%) received ISRT; in the combined-modality group, 3 (10%) received EFRT, 7 (24%) received IFRT, and 19 (66%) received ISRT. After a median follow-up of 6.2 years, 15 patients relapsed (13 distant, 2 locoregional). Five-year PFS and OS rates were 86% and 96% and did not differ by treatment. In the RT-only group, follow-up was shorter in the ISRT cohort (2.6 years vs 17.9 years [EFRT] and 8.5 years [IFRT], P < .01), but 5-year PFS did not differ by field size (P = .20). Locoregional control rates were 100% for the RT-only and combined groups, and corresponding 5-year DDFS rates were 93% and 95% (P = .95). Eight patients (11%) experienced a second malignancy (1 within RT field). Six patients died (1 from lymphoma). Use of limited ISRT fields does not appear to increase the risk of locoregional relapse, even when RT is given as single-modality therapy.