Predictive and prognostic role of volumetric analyses and lymphoma dissemination in pediatric HL: a prospective, multicenter, cohort study.

PURPOSE

The aim of the present trial is to investigate the predictive and prognostic role of PET volumetric parameters and maximal dissemination (Dmax) in pediatric Hodgkin lymphoma (HL).

MATERIALS AND METHODS

This is a prospective, multicenter study conducted in 35 AIEOP centers. Between March 2018 and December 2020, pediatric HL patients undergoing the same therapeutic trial have been enrolled. Patients underwent PET at baseline (PET0), for early (ERA), and late response assessment (LRA). The parameters analyzed were SUVmax, SUVmean, Dmax, TMTV (total metabolic tumor volume), TLG (total lesion glycolysis), and their (Δ) variations at different timing. Clinical and imaging parameters have been correlated to response, classified into adequate (AR) and inadequate (IR), based on protocol definition, and the event-free survival (EFS).

RESULTS

Overall, 300 patients were enrolled: 144 were male (48%), 167 stage I-II and 133 stage III-IV, 114 presented with bulky masses (> 200 ml), whereas 167 patients showed B-symptoms. All PET0 parameters resulted significantly correlated to ERA PET. With respect to the outcome, volumetric parameters and Dmax resulted prognostic at PET0, while semi-quantitative parameters and Dmax resulted prognostic at ERA PET. At multivariate analyses, an independent prognostic role was proven for stage (p = 0.0026), bulky volume (p < 0.0001), and Dmax (p = 0.0388) at PET0. Whereas, Dmax (p = 0.0025) and ΔSUVmax (p = 0.0297) resulted independent prognostic factors at ERA. By combining factors, we found a significant difference for patients with no risk factors at PET0 compared to patients with three risk factors (HR 17.701; p < 0.0001). At ERA PET, the poorest outcome was reached in case of bi-factorial risks, with a mean EFS of 56.4 months (HR 23.489; p < 0.0001).

CONCLUSIONS

To our knowledge, this is the first large, prospective, multicenter study of its type in pediatric patients. Our findings demonstrate the role of PET volumetric parameters in pediatric HL. Moreover, as first evidence in children, Dmax showed a proper predictive and prognostic role in HL. By combining these factors, we could stratify patients into risk-groups based on the outcomes.