The surgical management of rectal cancer includes a Total Mesorectal Excison (TME); depending on the height of the tumor, the problem of preservation of the anal sphincter arises, being able to perform a low anterior resection, an ultra-low anterior resection (RAUB) or an intersphincteric dissection. In some cases invading the sphincters or the puborectalis muscle, an abdominoperineal resection needs to be performed, being the gold standard in this particular situation so far.

TME can be performed by open, laparoscopic, robotic or transanal approaches, as long as the oncological principles for the resection are achieved. Unfortunately, up to 90% of these patients will present a change in bowel habit, ranging from an increased frequency of bowel movements to the degree of fecal incontinence or evacuation dysfunction. Of these patients, 25-50% will have a severe alteration in the quality of life. This wide spectrum of symptoms has been called "low anterior resection syndrome" (LARS). Other collateral damage is the change in sexual and urinary function, due to hypogastric plexus injury. There is a significant lack of multicenter prospective studies that provide evidence, and that reveal the functional results and quality of life of these techniques available to date for the management of rectal cancer.

The study is set up as a prospective multicentre observational study. Inclusion criteria are: 1) patients over 18 years old, 2) diagnosed with rectal cancer located below the peritoneal reflection, defined by preoperative MRI, 3) undergoing Open, laparoscopic, robotic or Transanal Total Mesorectal Excision (taTME) approaches, 4) with/without derivative stoma and 5) with/without neoadjuvant treatment. Exclusion criteria are: 1) Upper rectal cancer, located above the peritoneal reflection, 2) previous radical prostatectomy, 3) previous pelvic radiotherapy, 4) rectal resection without primary anastomosis, 5) intraoperative findings of peritoneal carcinomatosis, 6) stage IV disease, 7) multivisceral or en-bloc resection, which includes uterus, prostate, vagina or bladder, 8) rectal resection due to a benign condition, 9) rectal resection due to a recurrence of rectal cancer (previous anterior resection or another primary neoplasm), 10) rectal resection following a 'watch & wait' program, 11) emergency surgery, 12) previous derivative colostomy 13) inflammatory bowel disease.

Accepting an alpha risk of 0.05 and a beta risk of 0.2 in a two-sided test, 45 subjects are necessary in first group and 45 in the second to recognize as statistically significant a difference greater than or equal to 2 units. The common standard deviation is assumed to be 3. It has been anticipated a drop-out rate of 20% Primary outcomes are LARS and Vaizey score. Secondary outcomes included are QLQ C30 and CR29, sexual function questionnaire (female/male), urinary function questionnaire and postoperative complications (Clavien-Dindo classification) Data will be collected in an online secure and protected repository (Castor edc). The planned study period is 2 years (September 2021 - September 2023).

It is essential to have a validated instrument that allows us to assess sphincter function and the different aspects of quality of life in operated patients, since increased survival in this pathology has led to greater importance in the evaluation functional outcome and quality of life; Furthermore, there are recent studies that speak of the direct relationship between these factors.

Inclusion Criteria:

• Patients over 18 years old
• Informed consent
• Diagnosed with rectal cancer located below the peritoneal reflection, defined by preoperative MRI
• Open, laparoscopic, robotic or Transanal Total Mesorectal Excision (taTME) approaches
• Patients with/without derivative stoma
• Patients with/without neoadjuvant treatment

Exclusion Criteria:

• Upper rectal cancer, located above the peritoneal reflection
• Previous radical prostatectomy
• Previous pelvic radiotherapy
• Rectal resection without primary anastomosis
• Intraoperative findings of peritoneal carcinomatosis
• Stage IV disease
• Multivisceral or en-bloc resection, which includes uterus, prostate, vagina or bladder
• Rectal resection due to a benign condition
• Rectal resection due to a recurrence of rectal cancer (previous anterior resection or another primary neoplasm)
• Rectal resection following a 'watch & wait' program
• Emergency surgery
• Previous derivative colostomy
• Inflammatory bowel disease

Participants that meet the criteria will be identified in each centre