PSMA PET Registry (18F-DCFPyL)

Prostate cancer (PCa) is the most common cancer among Canadian men. Men diagnosed with localized PCa are placed in low, intermediate and high-risk groups, using the prognostic variables including pathologic Gleason score, T-stage and serum prostate specific antigen (PSA). These risk groups correlate with biochemical failure-free survival and prostate cancer specific mortality [1]. Although PCa is prevalent, the risk of clinical or fatal PCa in a 50 year old man is estimated at only 10% and 3%, respectively [2]. Currently, over 2/3 of men diagnosed with PCa are diagnosed with organ confined, low risk disease (PSA < 10 ng/ml, Gleason score (=GS) 3+3, cT1c) [3]. Management is dependent on tumor grade, size and stage and clinical parameters (e.g. life expectancy) and may range from active surveillance to radical therapy including definitive whole gland treatment (radical prostatectomy (RP), or radiotherapy). Although radical whole gland therapy is effective from an oncological standpoint, it may be associated with significant side effects. A more conservative approach in select patients may be enrollment in an active surveillance program. The concept behind this approach is that small volume, low grade PCa may have an indolent course and may not progress to biological significance in the absence of treatment in the patient's lifetime.

Rationale for this study is to determine in a prospective cohort of patients with unfavorable intermediate-risk or high-risk PCa, whether PSMA PET improves the detection of lymph node and distant metastases as compared to conventional imaging strategies (CT abdomen and bone scintigraphy).

To determine the rate of change in planned management after adding information from PSMA PET in patients with PCa being staged prior to primary therapy or restaged after primary therapy.

The central hypothesis behind the Princess Margaret Cancer Centre PSMA PET registry is that in patients with PCa, PSMA PET will enable more accurate staging and restaging, and improve prognostic stratification as compared to conventional workup. Furthermore, the investigators hypothesize that the addition of PSMA PET to the workup of these patients will change the planned management in a significant proportion of patients.

Primary Objective:

To determine in a prospective cohort of patients with unfavorable intermediate-risk or high-risk PCa, whether PSMA PET improves the detection of lymph node and distant metastases as compared to conventional imaging strategies (CT abdomen and bone scintigraphy).

To determine the rate of change in planned management after adding information from PSMA PET in patients with PCa being staged prior to primary therapy or restaged after primary therapy.

Secondary Objective:

To determine the clinical outcome and rate of biochemical control after therapy. For this purpose, information from clinical notes of routine clinical visits, results of blood tests (such as serum PSA) and follow-up imaging, if performed, will be collected for up to 5 years.

Inclusion criteria

• Patients will be eligible for inclusion in this study if they meet all of the following criteria:
• Age ≥ 18 years
• Histologic diagnosis of carcinoma of prostate
• Being staged or restaged for any of the following indications:

A. Staging of patients with:

i. High risk disease; defined as at least one of the following: a. Gleason ≥8, b. ≥T3 disease, c. PSA >20 ng/ml; ii. Unfavourable intermediate-risk disease defined as: a. more than one intermediate-risk factor (cT2b/ cT2c; GS=7; serum PSA of 10-20 ng/ml); or b. Gleason score of 4+3=7 or more; or c. greater than 50% positive biopsy cores.

B. Staging or restaging of PCa with equivocal findings on conventional workup:

i. Patients with PCa being staged or restaged with equivocal findings on conventional workup (CT, bone scan, MRI); to help guide management or select appropriate site for biopsy to establish disease status.

C. Restaging of patients with:

i. Biochemical failure (BCF) after primary therapy (radical prostatectomy or primary radiotherapy), or ii. BCF after salvage therapy/therapies when further treatment is being considered or iii. Pathologically involved nodes at time of radical prostatectomy or iv. Persistently detectable PSA (>0.1 ng/ml) >3 months after prostatectomy 5.1.4 Ability to provide written informed consent to participate in the study

Exclusion criteria

• Patients will be ineligible to participate in this study if they meet any of the following criteria:
• Inability to lie still for PET/CT or PET/MR examination
• For patients undergoing PET/MR only, any contraindication to MRI as per Joint Department of Medical Imaging policies (this exclusion criterion would not exclude patient from enrolling in the registry and undergoing PET/CT).
• Patients with documented, clear-cut metastatic disease on conventional workup where PET findings would not potentially alter patient management. In case of uncertainty, the patient will be discussed at multidisciplinary tumor boards and a majority decision will be made