Abstract 678P
Background
The role of metastasis directed therapy (MDT) is raising attractiveness in the setting of oligometastatic disease, and especially in the setting of oligorecurrent prostate cancer (PC), new metabolic tracers allow a superior detection of the real disease burden. The present analysis aims to compare the impact of 18F-Choline and 68Ga-PSMA PET-CT guided (MDT) in castration-sensitive oligorecurrent prostate cancer (PC) patients.
Methods
Inclusion criteria were: i) histologically-proven prostate adenocarcinoma, ii) evidence of biochemical relapse after primary tumor treatment, iii) ≤3 hypermetabolic oligorecurrent lesions detected by 18F-Choline or 68Ga-PSMA PET-CT, iv) PET-CT imaging performed in a single Nuclear Medicine Department, v) patients treated with upfront-SBRT without hormone-therapy, vi) SBRT delivered with a dose per fraction ≥5 Gy. In the case of oligoprogression (≤3 lesions outside the previous RT field) after MTD, further SBRT course was proposed; otherwise, androgen deprivation therapy (ADT) was administered.
Results
118 lesions in 88 patients were analyzed. Forty-four (50%) patients underwent 68Ga-PSMA PET-guided SBRT, and the remaining underwent Choline PET-based SBRT. The median follow-up was 25 months (range, 5-87), for the entire cohort. Overall Survival and Local Control were both 100%. Distant progression occurred in 48 patients (54.5%), for a median DPFS of 22.8 months (14.4-28.8). Median pre-SBRT PSA was 2.04 ng/ml in the Choline PET cohort and 0.58 ng/ml in the PSMA-PET arm. Disease-free survival rates were respectively 63.6% and 34% in the 68Ga-PSMA and Choline PET group (p=0.06). The ADT administration rate was higher after Choline-PET guided SBRT (p=0.00) due to the higher incidence of polymetastatic disease after first-course SBRT compared to 68Ga-PSMA-based SBRT.
Conclusions
In the setting of oligorecurrent castration-sensitive PC, PSMA-PET-guided SBRT produced a higher rate of ADT-free patients when compared to the 18F-Choline-PET cohort. Randomized trials are advocated.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.