To determine the best predictor of response and PFS among various methods and variables of tm metabolic measurements at baseline and at interim PET/CT compared to conventional methods in cHL.

Retrospective evaluation of prospectively acquired data in 40 cHL pts, all stages. Eligibility: PET/CT prior to and after 1 cycle (PET1), ABVD therapy, imaging at 60min+15min. Baseline parameters included clinical data (stage, IPS, unfavorable vs favorable), metabolic tm volume (MTV), total lesion glycolysis (TLG), SUVmax, SULpeak determined using 42% threshold and gradient methods (PETVCAR2, GE Healthcare). Data were evaluated at PET1 using Deauville 5-PS¹, %Δ in MTV, SUVmax, TLG, and SULpeak (PERCIST)². Variables were correlated with PFS and response evaluated by rIWG³.

Median follow-up: 31.2 mo. Results for PFS are displayed in Table 1. No baseline clinical or PET variable had association with PFS using either 42% threshold or gradient method. The best predictor of PFS was Deauville 5-PS at PET1, followed by %ΔSUVmax. PERCIST trended toward significance. %ΔMTV was predictive of PFS with 42% method, but not with gradient method. %ΔTLG was not predictive. There was a trend for baseline SUVmax to predict best response (42% threshold). At interim, %ΔSUVmax (42% threshold) was the best predictor of response, followed by PERCIST and %ΔSUVmax (gradient).

Deauville 5-PS best predicts PFS, while %ΔSUVmax best predicts response. Risk-stratification of cHL using tumor metabolic volumetry and PERCIST criteria may require a larger sample size and further assessment of various methodologies.