Abstract T050

Nodular lymphocyte predominant Hodgkin lymphoma in the Nordic countries – characteristics, treatment and survival

Background: Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a rare cancer. While initial response to treatment is typically excellent, late relapses occur and transformation to aggressive B-cell lymphomas is a feared complication.

Aim: To investigate relapse patterns, transformation rate, and overall survival (OS) in patients diagnosed with NLPHL in Denmark, Finland, and Sweden.

Method: In each country, population-based data were identified in nationwide registers from 2000 until 2018-2022, depending on data availability. Follow-up was until 2022-2023. Data on treatment, OS, relapse- and transformation rates were collected from medical records. The Kaplan-Meier estimator was used to calculate OS, progression-free survival (PFS), and median time to first relapse.

Results: A total of 752 NLPHL patients were identified (155 Denmark, 344 Finland, and 253 Sweden). The median age at diagnosis was 46–51 years, with follow-up ranging from 8.2–10.0 years. A male predominance >70% was seen, and the majority >67% of patients presented with limited-stage.

The ten-year OS was 85.3%, 86.6%, 85.6%, and the ten-year PFS was 73.0%, 63.5%, and 68.7% for Denmark, Finland, and Sweden respectively (Figure 1). NLPHL progression or relapse occurred in 19% of the cohort combined with median times to first relapse rangeing from 2.9–4.5 years. Transformation was recorded in 4%.

Most patients were treated with radiotherapy alone, 37%, 36%, and 23% in Denmark, Finland, and Sweden respectively. Rituximab containing treatment was administered in 16%, 25%, and 51% of patients in Denmark, Finland, and Sweden, whereas combined treatment modalities (chemo-, radiotherapy, and rituximab) were given in 8%, 26%, and 16% of patients respectively. In Sweden, rituximab use increased over time with 9% receiving rituximab only. Only one patient received rituximab monotherapy in Denmark. Combined radio-chemotherapy was given to 14% in Denmark and 15% in Sweden, and radiotherapy postoperatively to 5% in Denmark. In all countries, ABVD was the most common chemotherapy used.

Conclusion: NLPHL were treated with a variety of modalities; radio- and chemotherapy above all. Rituximab use increased over time, particularly in the later periods in Sweden. Outcome in terms of OS and PFS were good and comparable across the regions. The low relapse rate (15-22%) and transformation rate (3.2-4%) reflect population-based, long-term follow-up and indicates long-lasting remissions.