3577 Background: 20 to 50% of prostate cancer (PCa) patients undergoing radical prostatectomy (RP) or definitive radiation therapy (dRT) will experience disease recurrence. However, anatomical recurrence patterns may differ depending on the therapeutic approaches. The aim of this post-hoc retrospective analysis was to investigate if the relapse pattern as assessed by 68Ga-PSMA-11 PET/CT was different depending on the type of local pelvic therapy (RP, dRT, salvage RT (SRT), pelvic lymph node dissection (PLND), pelvic lymph node RT (PLNRT)) in patients with non-metastatic castrate sensitive (nmCS) recurrent disease after primary definitive therapy. Methods: Patients who underwent a 68Ga-PSMA-11 PET/CT for nmCS PCa recurrent disease after primary definitive therapy were screened from a database of 4 prospective studies (NCT02940262, NCT03515577, NCT04050215, NCT03582774). Patients who underwent primary staging (n = 95), without definitive therapy (n = 68), with known metastatic disease (M1) (n = 68) or with castrate resistant (CR) disease (n = 291) were excluded. We examined the relationship between recurrence patterns as assessed by 68Ga-PSMA-11 PET/CT (PROMISE criteria) and prior local treatments: i) RP, ii) dRT, iii) RP + SRT. Results: 787 patients were included in the analysis. Positive scan rates were 60%, 94% and 75% in RP, dRT and RP + SRT populations, respectively. Median pre-scan PSA levels were 0.50 (0.02-72.5) ng/ml, 4.4 (0.1-202) ng/ml, and 1.07 (0.04-33) ng/ml for patients who underwent RP (n = 464), dRT (n = 109) and post-RP SRT (n = 214). Median time to first recurrence was 27.7 after RP and 54.6 months after dRT (p = < 0.0001). Patients who underwent RP had lower local recurrence (LR) pattern (T+) rates by PSMA PET than those with dRT (99/464; 21% vs 69/109; 63%; p = < 0.0001). Nodal metastasis (N1) positivity rate was similar between RP and dRT (179/464; 39% vs 43/109; 39%; p = 0.87). Extrapelvic metastasis (M1) positivity rate was lower for RP than dRT (93/464; 20% vs 51/109; 47%; p = < 0.0001). Median time from post-RP SRT to second recurrence was 22.3 months. In patients who had a second recurrence after RP and SRT the positivity rate of LR (T+), N1 disease and M1 disease by PSMA PET/CT was 12% (24/214), 46% (99/214) and 44% (95/214). Conclusions: In this cohort of patients with nmCS PCa recurrent disease after primary definitive therapy, the patterns of failure differ based on prior local treatments.
Comparison Of Recurrence Patterns After Surgery And Radiation Therapy With 68Ga-PSMA-11 PET/CT In Non-Metastatic Castrate Sensitive Prostate Cancer Patients: A Single Center Post-Hoc Retrospective Analysis In 787 Patients
