After radical prostatectomy, 30-60% of patients will develop recurrent disease. Salvage radiotherapy, usually at 2 Gy per fraction, is the main treatment option for these patients.

The aim of the present study is to determine the 3-yr biochemical failure free survival of the stereotactic approach in 5 fractions in the context of salvage radiotherapy for biochemical failure after radical prostatectomy.

The present study aims at delivering 30 Gy to the prostatic bed in 5 fractions. At the same time, the pelvic nodes will be covered to 25 Gy, but in those patients considered at low risk of nodal involvement. In patients with evidence of macroscopic disease at the tumor bed through DCE-MRI, 40 Gy will be delivered in 5 fractions.

Selected patients will receive 6-month LHRH analogue preceded by Bicalutamide tablet 50 mg, daily, for 2 weeks to control for possible tumor flare.

Inclusion Criteria:

• - Able and willing to provide informed consent;
• Pathologically proven diagnosis of prostatic adenocarcinoma;
• Biochemical failure (2 consecutive PSA rises above 0.2 ng/ml) after radical prostatectomy;
• No regional or distant metastases;
• Eastern Cooperative Oncology Group performance status 0-1

Exclusion Criteria:

• - Previous local treatment of the prostate with radiotherapy, brachytherapy, cryosurgery, high-intensity focused ultrasound or cryotherapy;
• Previous radiotherapy to the pelvis;
• Previous or current symptomatic vesicourethral anastomotic stenosis post-RP (weak stream, straining to void, hesitancy and incomplete bladder emptying);
• PSA level at sRT> 2 ng/ml;
• (Each single) Lesion volume within the prostatic fossa at mpMR >5 cc;
• Previous chemotherapy for malignancy in past 5 years;
• Previous androgen deprivation for biochemical failure after RP;
• Contraindication to short term AD (in case of Px)
• Presence of nodal or distant metastasis, as confirmed by magnetic resonance (MR) or PET/CT
• Pathologically positive lymph nodes (pN+) at RP;
• Serious medical comorbidities or other contraindications to radiotherapy
• Presence of active inflammatory bowel disease;
• Presence of active connective tissue disease;
• Unable or unwilling to complete quality of life questionnaires