A prospective provincial registry of PSMA PET CT for recurrent prostate cancer (PREP): Results for 4135 men.
Authors: Bauman Glenn , Rashid Mohammed , Langer Deanna L , MacCrostie Pamela , Green Bo , Mak Victor , Kulkarni Girish S. , Shayegan Bobby , Klotz Laurence , Pautler Stephen E. , Finelli Antonio , Hagerty Marlon , Luke William , Kohan Andres , Tan Vivian S , Lavallee Luke , Zukotynski Katherine , Chin Joseph , Metser Ur 
Published: February 2025

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.