“Use of PET-CT with Gallium-68 labelled prostate Specific Membrane Antigen in the Diagnosis and Follow-up of patients with Prostate Cancerâ€

Introduction:

Prostate cancer (PCa) is the most common solidmalignancy in men and the third leading cause of cancer-related death inwestern Europe and the United States. The biochemical recurrence (BR)defined as increasing the value of serum PSA after radical therapy, is a commonoccurrence and occurs in about 20-30% of patients treated with radicalprostatectomy (RP) and up to 60% in patients treated primary with externalbeam radiotherapy (EBRT). In accordance with the nomograms, localrecurrence in prostate bed after RP can be predicted with an accuracy of about80% in patients in whom there is a BR in more than 3 years after RP, a PSAdoubling time (PSADT)> 11 months, Gleason Score (GS) <7 and a pT3apN0 andpTxN1. In contrast, systemic recurrence can be predicted with an accuracy ofabout 80% in patients in whom there is a BR distance of less than 1 year afterRP, PSADT of about 4-6 months, GS> 7 and stage of pT3b and pTxpN1. Furtherstudies in the literature and conducted in larger patient populations with BRafter radical therapy, showed excellent diagnostic power of 68Ga-PSMAPET/CT  in restaging patients withbiochemical recurrence of the disease even when serum PSA values ​​very low. In recent months, the use of this tracer has been the subject ofparticular and growing interest of the scientific community [15-20]. Thisradiopharmaceutical has also showed high specificity (> 90%) in studiesusing histological analysis as a reference standard for validation of PETresults. Finally, none of the studies in the literature havereported adverse events or clinically detectable pharmacological effectsconcurrently and after executing the PET/CT 68Ga-PSMA. For thereasons explained above, the PSMA could be an excellent molecular target forthe development of radiotracers for PET/CT imaging that could detect earlyrelapse of disease. This type of information would be even more relevant especiallyin emerging countries and different heath care systems around the world.**Aim:**To evaluate the utility of 68Ga-PSMA PET/CT indetecting the presence of local and/ or systemic disease in early laboratoryrecurrence of 68Ga-PSMA PET/CT in detecting the presence of localand/ or systemic disease in early laboratory recurrence. Objectives:

Primary: To evaluate the sensitivity,specificity, positive predictive value (PPV) and negative predictive value (NPV)in detecting the presence of local and/ orsystemic disease in earlylaboratory recurrence.

Design: Observational, prospective, non-randomised, multi centre study

Inclusion criteria1. Patients with histologicallyproven diagnosis of PCa

2. Patients with PCa thatfollowing RP or EBRT (with or without any adjuvant therapy) with serum levelsof PSA between 0.2 ng/mL and 4 ng/mL, or PSA between 4-10 ng/mL with necessarynegtive imaging investigation (BS, MR, CT).

3. Gleason Score ≥ 7

4. Age ≥ 35 years

StudyDuration:

Total project period: 48 months(enrollment for 24 months and collection of follow up data for 24 months)

Study Site: TataMemorial Centre

Efficacy assessments68Ga-PSMA PET/CT findings will be compared with:

1. Histology (when necessary in thejudgment of the clinician as expected in the normal care pathway), usingultrasound-guided biopsy in suspected local recurrence in prostate bed orduring the pelvic lymph node dissection and / or Extraperitoneal in cases ofsuspected nodal recurrence

2. Comparison of PET data with thosederived from conventional imaging methods carried out under the normal carepathway, such as: CT with contrast, MRI pelvic multiparametric, axial MRI andbone scan.

3. Compared with clinical andlaboratory data (eg PSA serum) provided in the normal care pathway.

**Variables to be estimated –**Sensitivity, Specificity, PPV and NPV.