Sara Damiani

Objective. Radiolabelled PSMA PET/CT has demonstrated high diagnostic accuracy in staging patients with intermediate-risk prostate cancer (PCa). However, its role on long-term prognosis and outcome prediction in this risk-group remains poorly defined. This study aimed to evaluate survival outcomes and identify prognostic factors in intermediate-risk PCa patients staged with PSMA PET/CT before primary treatment. Methods. This is a retrospective, multicenter study of patients diagnosed with intermediate-risk PCa, both favourable (FIR) and unfavorable (UIR), who were staged using radiolabeled PSMA PET/CT to evaluate the extent of the disease before initiating appropriate treatment (either surgery, radiotherapy or systemic treatment), in the period between 2021 and 2024. Primary endpoints were biochemical recurrence (BCR) and radiological recurrence (RR). Survival was assessed using Kaplan-Meier analysis and log-rank tests. The event-free survival was established by using the time between PET/CT examination and the occurrence of the events. All statistical analyses were performed with MedCalc® version 23.3.7 and STATA 18.0/SE. Results. A total of 148 patients were enrolled across all the centers, 112 patients were treated exclusively with local treatment strategies (n = 84 surgery, n = 28 radiotherapy) and 36 with the addition or only with systemic treatment. After a median follow-up of 25 months, 30 (20.3%) patients experienced BCR and 15 (10.1%) RR. UIR patients showed significantly higher PSMA-positivity (20.8% vs 5.6%, p = 0.007) and significantly shorter BCR-free survival compared to FIR (p = 0.039). Extraprostatic PET-positivity (N + or M+) was associated with a trend toward poorer BCR and RR outcomes (p = 0.08). Within the intraprostatic PRIMARY score, score 5 nearly doubled the RR rate compared to score 4 (15.9% vs 8.2%). Main limitations include the retrospective design and relatively short follow-up. Conclusions. PSMA PET/CT may provide early prognostic information in patients with intermediate risk PCa. While its yield in FIR is marginal, molecular staging in UIR effectively identifies aggressive phenotypes at higher risk for early treatment failure, supporting its use to guide treatment intensification in this subgroup.

Background/Objectives: Assessing treatment response in neuroendocrine tumors (NETs) remains challenging. The multifactorial mechanism of action of peptide receptor radionuclide therapy (PRRT) further complicates response evaluation, particularly in the absence of standardized criteria. This study aimed to compare different imaging-based response assessment methods after PRRT and to explore their relationship with clinical outcomes, particularly progression-free survival (PFS). Methods: In this single-center retrospective study, we analyzed NET patients treated with PRRT between 2020 and 2024 who underwent [⁶⁸Ga]Ga-DOTATOC PET/CT before and after therapy, with a minimum follow-up of 12 months. Five response criteria were evaluated: (a) Krenning Score changes; (b) adapted PERCIST criteria (MORE); (c) ZP-normalized parameter; (d) qualitative visual PET assessment; and (e) RECIST-based morphological response on contrast-enhanced CT. Imaging findings were correlated with clinical outcomes. Nonparametric analyses were performed using the MedCalc^® software. Results: Thirty-one patients (median age 63 years; 17 males) with NET were evaluated after PRRT. Post-PRRT PET/CT was performed at a median of 3 months. Response rates varied across methods, with higher rates noted using functional imaging (MORE 66%, Visual PET 68%, ZP 70%) compared to RECIST (40%) and Krenning score (21%). After a median follow-up of 37 months, 58% of patients experienced disease progression. Although no significant association was found between the response criteria and progression (p > 0.05), functional imaging showed a trend toward better correlation with longer progression-free survival. Conclusions: Functional PET-based responsecriteria suggest association with progression-free survival compared to RECIST criteria and Krenning score changes. However, given the exploratory nature of the study and its methodological limitations, these observations should be considered hypothesis-generating only. They do not provide definitive evidence of superiority over established assessment methods and therefore should not be interpreted as practice-changing.