The study aims to evaluate the efficacy of percutaneous tibial nerve stimulation (PTNS) associated with conservative therapy (arm A) for the treatment of low anterior resection syndrome (LARS) compared with only conservative therapy (arm B).

The secondary aims are the evaluation of the following parameters:

• Effect of PTNS on manometric parameters
• Effect of PTNS on quality of life
• Effect of PTNS on the severity of fecal incontinence and / or obstructed defecation
• Safety of PTNS

The study is a prospective randomized clinical trial that compares two treatments in patients with LARS:

Arm A: PTNS + conservative treatment (based on predominant symptom) Arm B: only conservative treatment

The study is divided into two phases:

1. PRETREATMENT PHASE

   The patients with LARS score ≥ 21 after anterior resection of the rectum with sphincter-saving surgery for rectal cancer, will be submitted during the first visit of the study to :

   • Collection of personal data
   • Collection of medical records
   • Collection of data relating to the intervention of anterior resection of the rectum
   • Verification of the criteria for inclusion / exclusion
   • Collection of informed consent
   • Administration of the questionnaires European Organisation for Research and Treatment of Cancer - Quality of Life Questionnaire Cancer 30 (EORTC QLQ-C30), European Organisation for Research and Treatment of Cancer - Quality of Life Questionnaire Colorectal 38 (EORTC QLQ-CR38), Faecal incontinence severity index (FISI); Fecal incontinence quality of life questionnaire (FIQL), Obstructed defaecation syndrome (ODS) score questionnaire and Constipation-related quality of life questionnaire (CRQoL)
   • Endoanal ultrasound
   • Anorectal manometry

2. PHASE OF TREATMENT During the treatment phase, data related to the treatment and any treatment related-complications will be recorded on a special form Bowel function and quality of life will be assessed using the same questionnaires at the end of treatment. Even anorectal manometry will be repeated at the end of treatment.

It is expected to enroll approximately 12 patients.

Inclusion Criteria:

• Patients with LARS score ≥ 21 after anterior resection of the rectum with sphincter-saving surgery for rectal cancer;
• Age> 18 years;
• Obtaining informed consent.

Exclusion Criteria:

• Patients carrying ostomy;
• Patients with clinical or radiological evidence of local or distant tumor recurrence;
• Patients suffering from neurological disorders;
• Patients with Inflammatory Bowel Disease (IBD);
• Patients who have a pacemaker or defibrillator;
• Patients taking antiplatelet agents or anticoagulants;
• Patients unable to follow the procedures of the Protocol or to provide informed consent.