The purpose of this study is to assess the detection rate of local relapse after radical prostatectomy with either PSMA or 64Cu-PET/CTs and whether the delineation of relapsed lesions using both methods can facilitate/change the therapeutic strategy of the radiation oncologist

PET/TC is a diagnostic tool potentially able to detect, in a single session, both local and distant disease. However, the sensitivity of 18-F-PET/CT in the identification of relapse on the prostatic bed, varies greatly and depends on the value of PSA with which the examination is carried out, the size of the relapse in the lodge, the acquisition protocol and it is limited by the physiological hyperaccumulation of the tracer in the bladder. The sensitivity of 18F-Choline PET/TC in our hands is significantly higher than the one that is generally reported in the literature (76% with PSA values >1 ng/ml after radical prostatectomy), but still lower than the one of mpMR. PET/CT with 64Cu exceeds the limits of 18F-choline PET/TC in the study of the prostatic bed, as the tracer used (64Cu) is not excreted by urinary route and therefore does not accumulate in the bladder.

This study has the following objectives:

Primary objective: - To evaluate the detection rate of both 64Cu-PET/CT and PSMA-PET/CT of relapses in patients undergoing radical prostatectomy and subsequent biochemical recurrence;

Secondary objectives are:

• to assess any change in radiation therapy strategy in terms of lesion delineation and dose distribution at planning.
• to evaluate the performance of both methods (mpMR and PSMA/64Cu-PET/CT) in assessing the response to radiotherapy with or without androgen deprivation

Criteria: Inclusion Criteria:

• Localized prostate adenocarcinoma (M0), any PSA value, any Gleason Score
• Previous radical surgery with subsequent undetectable PSA (<0.2 ng/ml)
• Biochemical recurrence (two consecutive PSA values of at least 0.2 ng/ml)
• M0 to 18F-choline PET/TC
• Local relapse at mpMR
• Age>18 years
• Performance Status 0-1 according to ECOG
• Informed written consent Exclusion Criteria:
• Detectable PSA after surgery
• Secondary bone lesions from prostate cancer or M1
• Hormone therapy started before staging examinations
• Previous pelvic radiotherapy
• Crohn's disease or ulcerative colitis (active phase)
• Psychiatric diseases
• Contraindication to MRI (metal prostheses, pacemakers, claustrophobia, etc.)
• Presence of coxo-femoral implants

prostatic neoplasm