Inclusion Criteria:  I1: Age >= 18 years old. I2: Patient with prostatic adenocarcinoma with indication for first-line or post-operative radiotherapy (adjuvant or biologic recurrence).  I3: Patient able to practice a physical activity (certificate of aptitude for adapted physical activity).  I4: Life expectancy greater than 6 months. I5: Absence of chronic inflammatory intestinal disease or intestinal surgery. I6: Signed informed consent. I7: Patient covered by a medical insurance.  Exclusion Criteria:  E1: Patient does not understand and cannot read French. E2: Patient followed for a psychiatric pathology or presenting cognitive disorders.  E3: Inability to comply with study follow-up goegraphical, social or psychological reasons.  E4: Patient requiring tutorship or curatorship or patient deprived of liberty. E5: Participation to another clinical trial which may interfere with principal Endpoint assessment.