The objective of this study is to evaluate, in patients diagnosed with prostate cancer who undergo radical prostatectomy and who require postoperative radiotherapy, tolerance in terms of acute and chronic GU and GI toxicity and efficacy in terms of biochemical control and survival, as well as of quality of life, from a hypofractional external radiotherapy scheme, increasing the dose per fraction in a shorter period of time.

What the investigators present in this study is a hypofractionation scheme of 62.5 Gy in 25 daily fractions of 2.5 Gy / day, which was chosen to provide a biological equivalent dose (BED) of 166.67 Gy, comparable to the 163 Gy administered with a scheme Normally divided up to 70 Gy in daily fractions of 2 Gy / day Version 2.0, March 27, 2019

(assuming an α / β ratio of 1.5 Gy for prostate cancer). The BED in risk organs (mainly rectum and bladder) will be governed by the ratio used and will differ depending on whether acute or late toxicity is calculated. If selected an acute α / β of 10 Gy and a conservative α / β for late toxicity of 3 Gy, the standard fractionation will result in an acute BED of 84 Gy versus 78 Gy in the hypofractionation scheme and a BED of 116.67 vs. 114.5 Gy for late toxicity.

Therefore, what the investigators expect is a toxicity profile that is at least similar, if not slightly better, compared to the norm-fractionated scheme of 70 Gy in 35 fractions and similar rates of biochemical control and survival.

To all this is added the use of intensity modulated radiotherapy and image-guided radiotherapy techniques (IGRT) that will allow the investigators to significantly reduce the dose administered to risk organs.

Inclusion Criteria:

• Age ≥ 18 years.

• ECOG 0-1 status.

• Previous radical prostatectomy (any modality will be allowed) with or without lymphadenectomy.

• Histological confirmation of prostate adenocarcinoma in the prostatectomy specimen.

• pT2-T3 Version 2.0, March 27, 2019

• pN0-Nx

• Indication of postoperative RT:

  • Adjuvant RT: pT3 and / or positive margins with PSA <0.2 ng / ml. Delayed RT is considered (> 6 months from the date of surgery but PSA <0.2 ng / ml).
  • Rescue RT: exclusive biochemical recurrence, without evidence of macroscopic local, regional or distant disease, after surgery. Biochemical recurrence is considered PSA ≥ 0.2 ng / ml after undetectable levels, confirmed with a subsequent determination.

• PSA levels ≤ 2 ng / ml after, at least 45 days after surgery and 30 days before inclusion in the study.

• No clinical evidence of lymph node disease. The presence will be admitted by imaging tests of pelvic nodes ≤ 1 cm in its shortest axis.

• No evidence of disease in the prostatic fossa. If you doubt by digital rectal examination or CT, an MRI will be performed.

• No evidence of distant disease after performing a thoraco-abdominal-pelvic CT scan and bone scan.

• Reasonable follow-up possibilities.

• Ability to complete the EPIC-26 questionnaire.

• Written informed consent prior to inclusion in the study.

Exclusion Criteria:

• - Previous pelvic radiation therapy.
• Distant metastasis.
• Macroscopic residual tumor.
• PSA> 2 ng / ml.
• Pathological stage T4.
• Lymph node involvement.
• Pelvic or para-aortic nodules in the reevaluation images after surgery, except pelvic nodes ≤ 1 cm in their shortest axis.
• Indication of pelvic nodal RT. Version 2.0, March 27, 2019
• Severe urinary incontinence at the time of indication for radiotherapy.
• Uni / bilateral hip prosthesis
• Previous tumors, except non-melanoma skin carcinoma, and which are not free of disease for at least 3 years from the end of the treatment of said neoplasms. Bladder tumors are excluded in all cases.
• Genetic hyper-radio-sensitivity syndromes.
• Chronic inflammatory bowel disease or partial or radical cystectomy for any reason.
• Previously treated with androgen deprivation therapy for a period greater than 3 months.
• Previously treated with chemotherapy for prostate cancer.
• Life expectancy <5 years or severe comorbidity: unstable angina, congestive heart failure, transmural myocardial infarction requiring admission in the last 6 months, active infectious process, respiratory disease requiring hospitalization, liver failure (Child-Pugh Class B or C), HIV with a CD4 count <200 cells / ml, kidney failure requiring dialysis and immunosuppressed by other causes.