Efficacy of Repeat Stereotactic Radiation in Patients With Intraprostatic Tumor Recurrence

Inclusion Criteria: * Biochemical recurrence occurring at least 2 years after external radiotherapy for prostatic adenocarcinoma by the Phoenix definition (PSA nadir + 2 ng/mL) * T1-T2c and PSA ≤20 ng/mL and Gleason score ≤7 at initial diagnosis of prostate cancer before the initial/first treatment. * Recurrence of prostatic adenocarcinoma proven by histology following radiotherapy by transrectal or transperineal sextant biopsies of the two lobes of the prostate, with a minimum of 12 biopsies, irrespective of Gleason score. Biopsies of the seminal vesicles are optional. * Clinical stage T1-T2 on relapse; unilateral extracapsular extension (T3a) on MRI permitted except posteriorly relative to the rectum * Estimated clinical target volume (CTV) / prostate volume \< 0.5 based on imaging and biopsies * Pelvic and prostatic assessment by multiparametric MRI- Absence of pelvic or metastatic recurrence proven by choline PET scan * Performance status World Health Organization (WHO) 0-1 * PSA level ≤10 ng/mL at baseline (before salvage-SBRT) * PSA doubling time \>10 months * International Prostate Cancer Score (IPSS) ≤12 * Uroflowmetry with a maximum flow rate \>10 mL/s, a postvoid residual urine volume \<150 mL, and a urine volume \>150 mL. * No other anti-cancer treatment since the external radiotherapy administered as first-line treatment * No other anti-cancer treatment planned for the current recurrence * No contraindication to fiducial marker implants; haemostatic disorders must be corrected before implantation * Age \>18 years * Life-expectancy greater than or equal to 5 years (Lee scale) * Patient registered with a health insurance system * Patient who has signed the informed consent form * Patients willing and able to comply with the scheduled visits, treatment plan, laboratory tests, and other study procedures indicated in the protocol. Exclusion Criteria: * Lymph node or metastatic spread * Late post-radiotherapy urinary or gastrointestinal toxicity of grade ≥2 (following primary radiotherapy) * Other cancers in the last 5 years except for non-melanoma-type skin cancer * History of inflammatory bowel disease * Anticoagulant treatment * Contraindications to undergoing MRI * Prostate volume \>80 cc * Transurethral resection of the prostate (TURP) in the 6 months before registrations * Presence of rectal telangiectasia grade 3 classified by the Vienna Rectoscopy Score (obligatory rectoscopy) * Previous rectal surgery * Patients unable to undergo medical follow-up in the study for geographical, social or psychological * Person deprived of their liberty or under protective custody or guardianship * Patients enrolled in another therapeutic study All patients during the SBRT planning with a ratio of clinical target volume (CTV) / prostate volume \>0.5 will be withdrawn from the study. These patients will be considered as not evaluable and will not be treated within the context of the study.