Baseline metabolic tumour burden improves risk stratification in Hodgkin lymphoma: A Children's Oncology Group study

The Children's Oncology Group AHOD0831 study used a positron emission tomography (PET) response-adapted approach in high-risk Hodgkin lymphoma, whereby slow early responders (SERs) received more intensive therapy than rapid early responders (RERs). We explored if baseline PET-based characteristics would improve risk stratification. Of 166 patients enrolled in the COG AHOD0831 study, 94 (57%) had baseline PET scans evaluable for quantitative analysis. For these patients, total body metabolic tumour volume (MTV), total lesion glycolysis (TLG), maximum standardized uptake value (SUV_max) and peak SUV (SUV_peak) were obtained. MTV/TLG thresholds were an SUV of 2.5 (MTV_2.5/TLG_2.5) and 40% of the tumour SUV_max (MTV_40%/TLG_40%). TLG_2.5 was associated with event-free survival (EFS) in the complete cohort (p = 0.04) and in RERs (p = 0.01), but not in SERs (p = 0.8). The Youden index cut-off for TLG_2.5 was 1841. Four-year EFS was 92% for RER/TLG_2.5 up to 1841, 60% for RER/TLG_2.5 greater than 1841, 74% for SER/TLG_2.5 up to 1841 and 79% for SER/TLG_2.5 greater than 1841. Second EFS for RER/TLG_2.5 up to 1841 was 100%. Thus, RERs with a low baseline TLG_2.5 experienced excellent EFS with less intensive therapy, whereas RERs with a high baseline TLG_2.5 experienced poor EFS. These findings suggest that patients with a high upfront tumour burden may benefit from intensified therapy, even if they achieve a RER.