Stage I-II Nodular Lymphocyte-Predominant Hodgkin Lymphoma: a Multi-institutional Experience of Adult Patients by ILROG.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is an uncommon histologic variant, and the optimal treatment for stage I-II NLPHL is undefined. We conducted a multi-center retrospective study including patients ≥16 years with stage I-II NLPHL diagnosed from 1995-2018 receiving all forms of management including radiotherapy (RT), combined modality therapy (CMT=RT+chemotherapy), chemotherapy (CT), observation after excision, rituximab and RT, and single agent rituximab (R). End points were progression-free survival (PFS), freedom from transformation, and overall survival (OS) without statistical comparison between management groups. We identified 559 patients with median age 39 years, 72.3% being male, and 54.9% having stage I disease. Median follow up was 5.5 years (IQR=3.1-10.1). 5-year PFS and OS for the entire cohort were 87.1% (95%CI=83.6-90.0%) and 98.3% (95%CI=96.4-99.2%), respectively. Primary management was RT alone (n=257, 46.0%), CMT (n=184, 32.9%), CT alone (n=47, 8.4%), observation (n=37, 6.6%), rituximab and RT (n=19, 3.4%), and rituximab alone (n=15, 2.7%). 5-year PFS rates were 91.1% (95%CI=85.3-94.7%) after RT, 90.5% (95%CI=84.8-94.1%) after CMT, 77.8% (95%CI=61.3-88.0%) after chemotherapy, 73.5% (95%CI=50.6-87.0%) after observation, 80.8% (95%CI=41.0-95.1%) after rituximab and RT, and 38.5% (95%CI=14.0-62.8%) after rituximab alone. For the RT cohort but not the CMT cohort, variant immunoarchitectural pattern and number of sites>2 were associated with worse PFS (P<0.05). Overall, 21 patients (3.8%) developed large cell transformation, with a significantly higher transformation rate for those with variant immunoarchitectural pattern (P=0.049) and number of involved sites >2 (P=0.0006). OS for patients with stage I-II NLPHLwas excellent following all managements.