3677 - Outcomes in Proton Therapy Use for Pediatric Patients with Hodgkin Lymphoma
Presenter(s)
D. N. Martir1, D. J. Indelicato2, A. Bechtel3, M. Bansal3, W. Slayton4, J. B. Dean5, C. G. Morris1, N. P. Mendenhall1, and R. Mailhot Vega1; 1Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, FL, 2Department of Radiation Oncology, University of Florida, Jacksonville, FL, 3Pediatric Hematology/Oncology, Nemours Children's Health, Jacksonville, FL, 4Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, 5Johns Hopkins All Children's Hospital, St. Petersburg, FL
Purpose/Objective(s): Hodgkin lymphoma is associated with favorable prognosis and high overall survival. Proton therapy (PT) represents a radiation modality particularly recommended for young patients due to its reduction in exit dose, with a goal to minimize late effects. We investigated the outcomes of patients receiving chemotherapy followed by consolidative PT for classical Hodgkin lymphoma (cHL) at initial diagnosis or relapse/refractory (R/R) disease.
Materials/Methods: We conducted a single-institution retrospective analysis of patients with cHL treated with consolidative PT from October 2007 to December 2022. Patients aged 0–22 years, enrolled in IRB-approved outcomes tracking protocols or registry studies, who received consolidative radiation therapy (RT) at initial diagnosis or R/R disease were included. Overall survival (OS) and relapse-free survival (RFS) were estimated using the Kaplan-Meier method. Crude cumulative incidence estimates were used to describe failure patterns.
Results: Seventy-four patients of 78 eligible were included, with 61 (82%) treated at initial diagnosis and 13 (18%) receiving RT for R/R disease. Median follow-up was 5.3 years. The median age at diagnosis was 16 years (range, 6.3–21.7), with most being female (58%) and having nodular sclerosing subtype (82%). Stage distribution: I (3%), II (58%), III (19%), IV (20%); 49% had B symptoms, and 78% had bulky disease. Risk group distribution is as follows: adult early favorable (2.7%), adult early unfavorable (9.5%), adult advanced (2.7%), COG low-risk (5.4%), COG intermediate-risk (37.8%), COG high–risk (39.2%), and EURONET TG3 (2.7%). Mid-treatment PET/CT showed a complete response in 52% of patients. The median total radiation dose was 33 GyRBE (range,15–39.6 GyRBE), with 47% receiving a boost. No late grade 3 radiation-related toxicities were observed. The 5-year OS was 96% overall, 97% for patients treated at initial diagnosis, and 92% for those treated at R/R disease. The 5-year RFS was 88% overall, 87% for initial diagnosis, and 92% for R/R disease. Of the 61 patients treated for initial diagnosis, a total of eight experienced relapse with four (6.6%) out-of-field & in-field, 3 (4.9%) out-of-field, and one (1.6%) in-field. Of the 13 patients treated for R/R disease, one experienced an out-of-field recurrence.
Conclusion: Consolidative PT following chemotherapy is an effective and well-tolerated treatment for pediatric and young adult patients with cHL, demonstrating excellent 5-year OS and RFS, particularly in those treated at initial diagnosis. The absence of grade 3 radiation-related toxicities highlights the favorable safety profile of PT. These findings support PT as a consolidative treatment modality in this population, warranting further studies to assess long-term outcomes and late toxicities.