Comparative Analysis of Response-Adapted Radiotherapy in Patients with Early-Stage Classic Hodgkin Lymphoma

Introduction: Consolidative radiotherapy in the upfront management of patients with early-stage classic Hodgkin lymphoma (cHL) may differ widely among clinical institutions. While some centers routinely include radiotherapy as a standard treatment component in all patients with early-stage disease, others adopt a more customized, response-adapted approach. Additional, comparative retrospective analysis of response-adapted radiotherapy in patients with early-stage cHL within real-world settings may provide further valuable guidance in personalized treatment strategies.

Patients and methods: we conducted a retrospective study analyzing of medical records of patients diagnosed with early-stage cHL from 2011 to 2022. The data were collected from three tertiary care centers located in the Middle East, which allowed for a comprehensive analysis of the regional treatment approaches.

Two independent reviewers from each institution meticulously collected and cross-checked the patient data to ensure consistency and accuracy. We focused on comparing the outcomes of the two groups (radiotherapy vs. no radiotherapy), emphasizing key metrics such as complete remission and relapse rates. The primary endpoints of the study, overall survival and progression-free survival were calculated using the Kaplan-Meier method. The data were thoroughly analyzed using SPSS statistical software, offering robust insights into treatment outcomes and a deeper understanding of the effectiveness of various therapeutic strategies

Results:

A total of 490 patients met the inclusion criteria for this study, comprising 247 females and 243 males, with a median age of 27 years. The mean follow-up duration was 59 months. Most patients (68.2%) had nodular sclerosis subtype of classic Hodgkin lymphoma, and 87.8% were diagnosed with stage II disease, 12.2% had stage I. Furthermore, 64.9% of the patients presented with B symptoms.

In this cohort, 57.8% of patients received radiotherapy as part of their treatment protocol. At end of treatment, 87.8% of the entire cohort achieved complete remission (CR). However, 46 patients experienced a relapse: 21 of these patients did not receive radiotherapy, while 25 had received radiotherapy as consolidation therapy.

Among the 420 patients who achieved CR following first-line chemotherapy, 57% went on to receive consolidation with radiotherapy. Relapse rate was not statistically significant between patients in CR and received radiotherapy as consolidation (7.5%), compared to those who did not receive radiotherapy (7.2%) and reached CR at end of first-line chemotherapy.

A positive interim PET scan was observed in 25.7% of the total patients' population, and 23.8% of these patients still had active disease at the end of chemotherapy. For patients with both positive interim and end-of-treatment (EOT) PET scans, 66.7% underwent radiotherapy, and 30% of these developed relapsed or refractory (r/r) disease. Additionally, 57.9% of patients with a positive interim PET scan received radiotherapy, while 42.1% did not. Among those who did not receive radiotherapy, 15% developed r/r disease, compared to 17.8% of those who received radiotherapy, with no statistically significant difference between the two groups.

Ten patients with positive interim PET scan had negative EOT-PET scan and therefore did not receive radiotherapy. Among these patients, the rate of r/r disease was notably high at 60%.

As of the data cut-off in November 2022, there was no statistically significant difference in progression-free survival rates between patients who received radiation and those who did not. However, there were some subgroups who benefited from radiotherapy (a.e. positive EOT-PET). Overall survival was similar across both groups.

Conclusions: Our real-world data suggests that routine consolidation with radiotherapy is not necessary for patients with early-stage cHL who have negative EOT-PET results. However, for patients with positive EOT-PET scans, consolidative radiotherapy provides efficacy by curing a substantial proportion of these individuals, indicating its potential benefit in this population with higher risk of disease relapse. Additional data and further insights into these findings will be presented during the upcoming annual conference of American Society of Hematology 2024.

No relevant conflicts of interest to declare.