• Overall survival (OS) [ Time Frame: Up the end of SBRT until death for cancer or other causes up to 3 years ]
  From the end of RT treatment to the time of clinical progression or mortality from specific disease cause
• Biochemical progression-free survival (BPFS) [ Time Frame: up 3 months from the end of the treatment up to 3 years ]
  Biochemical progression is defined according to the EAU guidelines [18], namely a rising PSA level >0.2 ng/ml following radical prostatectomy and >2 ng/ml above the nadir after radiation therapy.
• Numbers of patients who experienced acute and late toxicity [ Time Frame: Up to 1 months after treatment completion and then up to 3 years ]
  Toxicity will be assessed according to the Common Toxicity Criteria for adverse events (CTCAE) toxicity criteria v4.3

A randomized phase II clinical trial (RADIOSA trial: Radioablation with or without Androgen DeprIvation therapy in metachronous prostate cancer OligometaStAsis).

The aim is to compare time to progression between the two study arms: SBRT only or SBRT and hormonotherapy (ADT). The primary objective is to compare the progression-free survival (PFS) defined as the absence of new metastatic lesions (local, regional or distant) between the two arms. The secondary endpoints include the comparison of overall survival (OS), biochemical progression-free survival (BPFS), ADT-free survival, local control, treatment-induced acute and late toxicity, time to castration-resistant disease and QoL between the two arms; the development of a dedicated biobanking (collection of plasma and serum) for further biological investigation of predictive/diagnostic factors for personalized treatment; the preliminary evaluation of prognostic biomarkers; the correlation between imaging-derived parameters and treatment outcome.

• Drug: Androgen deprivation therapy (ADT)
  SBRT + ADT
• Radiation: SBRT
  SBRT to all radiological documented lesions (bone or lymphnodes)

• Experimental: Stereotactic body Radiotherapy (SBRT) only
  ARM 1: salvage SBRT for lymph nodes and/or bone metastases. All the radiologically documented lesions will be treated simultaneously.
  Intervention: Radiation: SBRT
• Active Comparator: Stereotactic body Radiotherapy (SBRT) and hormonotherapy (ADT)
  ARM 2: salvage SBRT (as described for ARM 1) + 6-month ADT (luteinizing hormone-releasing hormone (LHRH) agonist or antagonist). ADT should start within one week before the start of SBRT.
  Interventions:

  • Drug: Androgen deprivation therapy (ADT)
  • Radiation: SBRT

Inclusion Criteria:

• Histologically proven initial diagnosis of adenocarcinoma of the prostate;
• Biochemical relapse of PCa following radical local prostate treatment (radical prostatectomy, primary radiotherapy or radical prostatectomy +/- prostate bed adjuvant/salvage radiotherapy) +/- ADT according to the European Association of Urology (EAU) guidelines 2016 [18] or after any salvage therapy if biochemical progression is diagnosed in the context of castration sensitive PCa;
• Nodal relapse in the pelvis, extra-regional nodal relapse (M1a), bone metastases (M1b) on Ch-PET/CT or WBMRI with a maximum of 3 lesions;
• Serum testosterone level >50 ng/dl at the time of randomization (castration sensitive PCa)
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1;
• Age ≥18 years;
• Written informed consent signed

Exclusion criteria

• Serious concomitant comorbidities or contraindication to SBRT and/or ADT;
• Previous invasive cancer (within 3 years before the prostate cancer diagnosis) apart from non-melanoma skin malignancies;
• No ability to complete questionnaires about QoL;
• Presence of mental diseases that cannot ensure valid informed consent;