A prospective provincial registry of PSMA PET CT for recurrent prostate cancer (PREP): Results for 4135 men.

35 Background: PREP was initiated in Ontario to provide access and characterize performance of PSMA PET CT among men with recurrent prostate cancer after primary definitive treatment (RP or RT). Methods: Between 03/18 and 09/22, 4135 men were accrued. Men were enrolled and imaged with 18F-DCFPyL at 1 of 6 participating sites within 1 of 6 clinical cohorts. Standardized reports delineated sites of recurrence and post PET management changes. Linkage to provincial databases allowed estimation of overall survival and utilization of salvage radiotherapy after PET. Results: Median follow-up was 1.8 years; key findings are in Table 1. Significant predictors of a positive PET scan on multi-variable analysis included: higher PSA at time of PET and clinical cohort (highest for cohort 4). Significant predictors of change in management were type of recurrence (highest for loco-regional) and higher PSA. Significant predictors of worse overall survival included clinical cohort (worst for cohort 4), extent and type of metastases (worst for mixed bone/lymph/visceral or extensive metastases). A change in management post PET was a significant predictor of improved survival. Conclusions: The PREP registry facilitated access to PSMA PET/CT with high rates of disease detection and impact on management. Significant factors associated with survival were extent and sites of disease detected and management change after PET. Clinical trial information: NCT03718260 . PREP registry: Key findings. Total (n=4135) Cohort 1 (n=255): BF within 3 months from RP and pN+ or PSA >0.1 Cohort 2 (n=1500): BF following RP Cohort 3 (n=1040): BF post RPand adjuvant or salvage RT Cohort 4 (n=263): BF while on salvage hormone therapy Cohort 5 (n=176): BF following Therapy for Oligo-metastases on prior PET Cohort 6 (n=901): BF following primary RT Median Age at scan (IQR) 71.0 (66.0–76.0) 66.0 (61.0–70.0) 70.0 (65.0–74.0) 72.0 (67.0–76.0) 74.0 (69.0–79.0) 73.0 (66.0–77.0) 75.0 (70.0–79.0) Median PSA (IQR) at scan (ng/mL) 1.3 (0.3–4.0) 0.7 (0.2–2.5) 0.3 (0.2–1.0) 1.1 (0.5–2.7) 3.5 (1.6–7.2) 2.4 (1.0–5.3) 4.4 (3.1–7.4) PET: Negative Findings 1216 (29.4) 84 - 88 (32.9 - 34.5)* 749 (49.9) 258 (24.8) 19 (7.2) 18 - 22 (10.2 - 12.5)* 84 (9.3) PET: Locoregional Recurrence 1377 (33.3) 95 (37.3) 471 (31.4) 295 (28.4) 63 (24.0) 34 (19.3) 419 (46.5) PET: Oligo-Metastatic (≤5 metastases) 1021 (24.7) 45 (17.6) 224 (14.9) 354 (34.0) 111 (42.2) 70 (39.8) 217 (24.1) PET: Extensive Metastases 521 (12.6) 29 (11.4) 56 (3.7) 133 (12.8) 70 (26.6) 52 (29.5) 181 (20.1) Change in management post PET 2070 (50.1) 135 (52.9) 585 (39.0) 552 (53.1) 152 (57.8) 99 (56.3) 547 (60.7) Radiotherapy within 6 months 1729 (41.8) 165 (64.7) 866 (57.7) 346 (33.3) 88 (33.5) 49 (27.8) 215 (23.9) Died during follow-up period 138 (3.3) 1 - 5 (0.4 - 2.0)* 18 (1.2) 30 (2.9) 35 (13.3) 8 -12 (4.5 - 6.8)* 44 (4.9) BF: Biochemical Failure; RP: Radical Prostatectomy; RT: Radiotherapy; IQR: Interquartile Range. *Small cell size.