Clinical Research Directory

Inclusion Criteria: * Men aged 18 to 70 * Patients undergoing surgery for cancer of the lower or middle rectum by total removal of the mesorectum with colorectal or coloanal anastomosis after neoadjuvant radiotherapy, with normal preoperative erectile function (defined by a combined IIEF erectile function domain score of at least 22). * Nerve-conserving surgery * Sexually active patient without treatment for erectile function prior to surgery * Presence of a regular sexual partner (male or female) * Adult having read and understood the information letter and signed the consent form * Membership of a social security scheme Exclusion Criteria: * T4 tumor or tumor requiring extended surgery * Patients with abnormal erectile function defined by a combined IIEF erectile function domain score of less than 22. * History of prostate cancer * Sleep disorders, patients taking sedatives/hypnotics * Contraindication to SILDENAFIL EG 50 mg, film-coated tablet * Contraindication to placebo * Patients already treated with PDE5 inhibitors * Patients suffering from SARS COV 2\* * Person deprived of liberty by an administrative or judicial decision or person placed under court protection / sub-guardianship or guardianship. * Any history of illness or psychological or sensory abnormality likely to prevent the subject from fully understanding the conditions required for participation in the protocol, or to prevent the subject from giving informed consent. * Person participating in another drug trial.