Published clinical evidence confirms that a single dose of 24 Gy provides unprecedented long-term local control in primary and metastatic prostate cancer with safe toxicity profiles, provided that exposure of surrounding healthy tissues is critically assessed with fulfillment of strict constraints and dose distribution is accomplished using image guidance and tracking tools. In the present trial, intermediate unfavorable and selected high-risk organ-confined prostate cancer patients will undergo Single Dose Radiation Therapy (SDRT) With Focal Boost to the MRI-defined Macroscopic Tumor Volume by means of image-guided volumetric intensity-modulated arc radiotherapy (IGRT-VMAT) and state-of-the-art treatment-planning and quality assurance procedures. Androgen Deprivation Therapy (ADT) type and duration has been set as per standard of care, in accordance with current recommendations and guidelines.

Patients enrolled in this observational prospective trial will be offered image-guided, volumetric modulated radiotherapy (IGRT-VMAT) in a single session (SDRT) of 21 Gy to the whole gland with a simultaneous boost of 24 Gy to the macroscopic PI-RADS driven (4-5) tumour(s). ADT will be prescribed concomitantly, as per standard of care. A real time non-ionizing prostate monitoring will be used to account for intra-fractional errors. If the dose constraints to the normal tissues are at risk, these will be prioritised over the aimed boost dose. The primary endpoint of the trial is the treatment related toxicity measured by the CTCAE v5.0. Secondary endpoints are quality of life in different domains (sexual, rectal , urinary) and biochemical outcome.

Patients will be followed at one month, then every 3 months for the first 12 months and every 6 months thereafter. Quality of Life will be prospectively evaluated through validated tools (ECOG, EPIC, IIEF-5, IPSS, ICIQ-SF) at various timepoints. Percentage or total mean score will be reported according the questionnaires, whether they grade values in a scale or use descriptive statistics. Kaplan-Meier curve analysis of biochemical relapse free survival (b-RFS) at 2 and 5-year bRFS for all patients will be estimated.

INCLUSION CRITERIA

• Histologically proven prostate adenocarcinoma;
• Intermediate and High risk disease, as per the NCCN definition;
• N0M0 at staging with standard techniques (Bone Scan and Abdominal CT) or (preferably) Choline or PSMA PET-CT;
• ECOG performance status between 0 and 2;
• Life expectancy of > 5 years, in the opinion of the investigator;
• IPSS score must be ≤ 19 (alpha blockers allowed);

EXCLUSION CRITERIA:

• ≥T3b disease according to the 8th AJCC classification;
• PSA>20 ng/ml at any time point;
• Previous local treatment of the prostate with surgery (radical prostatectomy or cryotherapy);
• Previous radiotherapy to the pelvis;
• Previous invasive malignancy unless disease free for a minimum of 5 years;
• Active Crohn's Disease or Ulcerative Colitis;

Unfavorable Intermediate and Selected High Risk Prostate Cancer (no cT3b and PSA > 20 ng/mL allowed), as per NCCN definition