24 Gy in One Fraction Urethral-sparing "HDR Like" SBRT for Prostate Cancer

Inclusion Criteria: * Histological diagnosis of prostate adenocarcinoma, International Society of Urological Pathology (ISUP) grade groups 1-5 * Patients over 18 years of age * Signed informed consent * Negative lymph nodes confirmed by imaging (PSMA PET/CT and/or pelvic MRI with and without contrast medium) where recommended by guidelines (intermediate and high risk patients, according to National Comprehensive Cancer Network (NCCN) guidelines) in the previous 3 months * Clinical M0 (PSMA PET/CT and/or bone scan and/or pelvic MRI with and without contrast medium in suspected patients and unfavorable intermediate and high risk patients, according to NCCN guidelines), in the previous 3 months * Acceptable uroflowmetry: peak urine flow index (peak flow preferably ≥ 15 ml/s), post voiding residue (PVR) ≤50 cc. If lower, acceptable if, by carrying out 3 months of neoadjuvant hormone therapy + alpha-lytic for the reduction of prostate volume, uroflowmetry is reset to at least ≥ 12 ml/s. * PS (ECOG) ≤2 * No previous pelvic radiotherapy * Other conditions necessary for the correct execution of the proposed treatment (ability to fill in the questionnaires for the evaluation of the Quality of Life EORTC QLQ-C30, EORTC QLQ-PR25, IPSS, IIEF-5, EPIC 26) Exclusion Criteria: * Serious systemic diseases * Psychic or other disorders that may prevent the patient from signing the informed consent * Previous invasive cancer, except skin cancer (excluding melanoma) unless patient free of disease for at least 3 years (e.g. carcinoma in situ of the oral cavity or bladder) * Lymph node disease (N1) * Evidence of distant metastases (M1) * IPSS questionnaire data \> 20 points * Uroflowmetry with maximum basal flow ≤ 11 ml/sec and/or PVR \>100 ml * Concomitant urinary/gastrointestinal inflammatory diseases (e.g. ulcerative colitis, Crohn's disease) * Overactive bladder * Impossibility of implantation of fiducials * Inability or refusal to place bladder catheter for simulation CT and MR * Inability to perform simulation MRI * Contraindication for hormonal treatment for patients with unfavorable intermediate, high or very high risk disease * Non-compliance with dose limits established in the treatment plan