MP48-13: The Key Role Of Concomitant Androgen-Deprivation Therapy On The Efficacy Of Imaging Guided Treatments In Men With Biochemical Recurrent Prostate Cancer After Radical Prostatectomy And Positive 68Ga-PSMA PET/CT Scan

Daniele Robesti*, Milano, Italy, Elio Mazzone, Milan, Italy, Giorgio Gandaglia, Armando Stabile, Giuseppe Rosiello, Alberto Martini, Carlo Andrea Bravi, Milano, Italy, Giuseppe Cirulli, Antony Pellegrino, Riccardo Leni, Milan, Italy, Francesco Barletta, Milano, Italy, Mario De Angelis, Milan, Italy, Simone Scuderi, Milano, Italy, Luigi Nocera, Milan, Italy, Daniele Raggi, Milano, Italy, Vito Cucchiara, Milan, Italy, Nazareno Suardi, Genoa, Italy, Andrea Necchi, Milano, Italy, Shahrokh F. Shariat, Vienna, Austria, Francesco Montorsi, Alberto Briganti, Milano, Italy

Introduction: The benefit of adding androgen-deprivation therapy (ADT) on imaging guided treatments (IGT) in men with biochemical recurrence (BCR) is a matter of debate. No study tested such combined approach in men diagnosed with recurrence at 68Ga-PSMA PET. To address this void, we assessed the impact of adding ADT to IGT on the risk of clinical recurrence (CR) in patients with positive a PSMA PET after surgery.

Methods: We retrospectively identified 207 patients evaluated with 68Ga-PSMA PET/CT for BCR after RP between 2016 and 2021. Of these, only patients with a positive PSMA PET and who received IGT were included. Early clinical recurrence (CR) was defined as any new metastases detected at imaging within 2-years after a first PSMA PET/CT. Multivariable Cox regression assessed the impact of ADT plus IGT in men with positive PSMA PET/CT on risk of CR, after adjusting for PSA at PSMA PET/CT, adverse pathological features (i.e. Grade Group 4-5 with = pT3a stage and/or lymph node invasion) and use of sRT. Multivariable Cox-derived Kaplan- Meier (KM) analyses depicted the time from the first scan to CR and progression to CRPC.

Results: Overall, 104 patients had a positive PSMA PET scan and received IGT. Median PSA at PSMA PET/CT was 0.6 ng/ml and 41 patients experienced disease progression. Overall, 76 (59%) received ADT. Use of ADT was left at the discretion of each treating physician. No differences were observed in terms of adverse pathology features and rate of salvage RT or IGT use between the ADT groups (all p=0.1). Median follow-up was 18 months after the PSMA PET/CT. The overall 2-year CR-free survival and CRPC-free survival rates were 60 vs 91% from the time of BCR. At multivariable analyses, concomitant ADT use at the time of salvage treatments was associated with reduced risk of CR (HR 0.45, p=0.01), after adjusting for confounders. At the Cox derived KM, the 2-year CR-free survival and 2-year CRPC-free survival rates were, respectively, 63 vs 31% in patients receiving ADT vs those patients not receiving ADT.

Conclusions: Even after accounting for cofounders, concomitant administration of ADT during IGT for a positive PSMA PET/CT scan represents a protective factor for further metastatic progression during follow-up.

Source of Funding: None