PET/CT Response Assessment in Pediatric Hodgkin Lymphoma: Does Deauville Score 3 Reflect Negativity?

Background: FDG PET is required for the staging and response evaluation of pediatric Hodgkin lymphoma. This study aimed to evaluate the outcomes of pediatric patients with Hodgkin's lymphoma based on interim PET CT assessments of early response following second-cycle chemotherapy using the Deauville score (DS). It also determines whether DS-3 is providing an adequate or inadequate response. Methods: We conducted a retrospective cohort study including 504 pediatric patients with classic Hodgkin lymphoma who were treated with chemotherapy based on the Euro-Net protocol at the Children Cancer Hospital Egypt from March 2019 till the end of October 2022. Results: Patients with adequate response DS 1/2 and DS 3 showed nearly the same 3-year event-free survival (EFS) of 91.9% and 91.5%, respectively, compared with those patients with inadequate response DS 4/5, who showed an EFS of 80.4% (P=0.001). Patients with a DS 3 at interim PET evaluation were considered negative as DS 1/2. Patients of DS 3 group who did not receive radiotherapy had a much worse 3-year EFS by the existence of positive B symptoms, an ESR>30, or an advanced stage. Radiation therapy did not improve the 3-year EFS in patients with an inadequate response (DS4/5) and poor prognostic characteristics. They still need more advanced treatment. Conclusion: DS 1/2 and DS 3 had about the same 3-year EFS, which is better than the 3-year EFS of patients with DS 4/5. Therefore, we can classify DS 3 as having negative FDG PET CT uptake.