The Comparative Prognostic Value of the Interim PET Deauville Score and ΔSUVmax in Classical Hodgkin Lymphoma: A Real-World Study of Imaging and Inflammatory Markers

Background: Interim [18F]FDG-PET/CT with the Deauville score (DS) is central to response assessment in classical Hodgkin lymphoma (cHL). Quantitative ΔSUVmax and the lymphocyte-to-monocyte ratio (LMR) may refine the DS, but ΔSUVmax thresholds vary across cohorts and have rarely been compared. We tested published ΔSUVmax thresholds and compared the value added by ΔSUVmax and the LMR to the DS for progression-free survival (PFS). Methods: We retrospectively analyzed 78 adults with cHL with paired baseline and interim PET/CT. Outcomes were measured from the interim scan using Kaplan–Meier analysis, Cox regression, and Harrell’s C-index with bootstrap validation. Results: Over 47 months’ median follow-up, 26 PFS events occurred. Higher published ΔSUVmax thresholds (83–88%) did not separate PFS, whereas 66% did; ΔSUVmax added no value to the DS. DS positivity predicted worse PFS (HR 2.26, p = 0.040). Lower LMR added value to the DS (HR 0.45, p = 0.006) but overlapped with the International Prognostic Score (IPS; ρ = −0.51) without surpassing it. A DS-plus-IPS model stratified three risk groups (5-year PFS 83%/60%/24%) and outperformed DS-plus-LMR (C-index 0.73 vs. 0.66). Conclusions: Published ΔSUVmax thresholds were not reproducible, and ΔSUVmax did not improve on the DS. The LMR added independent information but did not surpass the IPS; a simple DS-plus-IPS model provided effective, low-cost risk stratification.