We evaluated the prognostic role of the largest distance between two lesions (Dmax), defined by positron emission tomography (PET) in a retrospective cohort of newly diagnosed classical Hodgkin Lymphoma (cHL) patients. We also explored the molecular bases underlying Dmax through a gene expression analysis of diagnostic biopsies. We included patients diagnosed with cHL from 2007 to 2020, initially treated with ABVD, with available baseline PET for review, and with at least two FDG avid lesions. Patients with available RNA from diagnostic biopsy were eligible for gene expression analysis. Dmax was deduced from the three‐dimensional coordinates of the baseline metabolic tumor volume (MTV) and its effect on progression free survival (PFS) was evaluated. Gene expression profiles were correlated with Dmax and analyzed using CIBERSORTx algorithm to perform deconvolution. The study was conducted on 155 eligible cHL patients. Using its median value of 20 cm, Dmax was the only variable independently associated with PFS (HR = 2.70, 95% CI 1.1–6.63, pValue = 0.03) in multivariate analysis of PFS for all patients and for those with early complete metabolic response (iPET‐). Among patients with iPET‐low Dmax was associated with a 4‐year PFS of 90% (95% CI 82.0–98.9) significantly better compared to high Dmax (4‐year PFS 72.4%, 95% CI 61.9–84.6). From the analysis of gene expression profiles differences in Dmax were mostly associated with variations in the expression of microenvironmental components. In conclusion our results support tumor dissemination measured through Dmax as novel prognostic factor for cHL patients treated with ABVD.

Background We aimed to test whether the prognostic value of 18 F‐Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT) in metastatic castration-resistant prostate cancer (mCRPC) extends to the estimation of systemic treatment response duration. Methods mCRPC patients submitted to FDG-PET/CT in four Italian centers from 2005 to 2020 were retrospectively enrolled. Clinical and biochemical data at the time of imaging were collected, and SUV max of the hottest lesion, total metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were calculated. The correlation between PET- and biochemical-derived parameters with Overall Survival (OS) was analysed. The prediction of treatment response duration was assessed in the subgroup submitted to FDG-PET/CT in the six months preceding Chemotherapy (namely Docetaxel or Cabazitaxel, 24 patients) or Androgen-Receptor Targeted Agents (ARTA, namely Abiraterone or Enzalutamide, 20 patients) administration. Results We enrolled 114 mCRPC patients followed-up for a median interval lasting 15 months. While at univariate analysis, prostate-specific antigen (PSA), Alkaline Phosphatase (ALP), MTV, and TLG were associated with OS, at the multivariate Cox regression analysis, the sole MTV could independently predict OS (p < 0.0001). In the subgroup submitted to FDG-PET/CT before the systemic treatment initiation, PSA and TLG could also predict treatment response duration independently (p < 0.05). Of note, while PSA could not indicate the best treatment choice, lower TLG was associated with higher success rates for ARTA but had no impact on chemotherapy efficacy. Conclusions FDG-PET/CT’s prognostic value extends to predicting treatment response duration in mCRPC, thus potentially guiding the systemic treatment selection.