Objective: To analyze the survival of patients with a reduction in the number of resected LN in patients submitted to neoadjuvant and total excision of the mesorectum with rectal cancer.

Expected results:

Survival rate between patients Complete Pathologic Response with less than 12 LN and 12 or more LN.

To determine the difference in survival between patients with less than 12 LN in complete versus incomplete response.

According to the International Union Against Cancer a minimum of 12 lymph nodes (LN) should be obtained in the surgical specimen for colorectal cancer staging. Recent studies have reported that the use of neoadjuvant chemoradiotherapy (QRN) may result in failure to obtain the minimum number of LN in the piece in 30-52% of patients. Objective: To analyze the survival of patients with a reduction in the number of resected LN in patients submitted to neoadjuvant and total excision of the mesorectum with rectal cancer. Patients and methods: From January 2013 to January 2015, patients with rectal cancer were submitted to QRN (5-FU and 5040 Gys) followed by total excision of mesorectum with ligation of the inferior mesenteric vessels in their roots. Patients with T3, T4 and / or N + staging that were up to 10 cm from the anal border were included. Patients whose treatment with neoadjuvant chemoradiotherapy was incomplete or who had significant delays in re- staging and / or performing the surgery were excluded. All were staged by rectal examination, colonoscopy, chest and abdominal CT, and pelvic MRI, and also re-staged 8 weeks after neoadjuvant termination, operated and submitted to total excision of the mesorectum. The patients were divided into 4 groups: a) Incomplete pathological response with less than 12 LN. b) Incomplete pathological response with 12 or more LN. c) Complete pathological response with less than 12 LN. d) Complete pathological response with 12 or more LN. The possible variables related to the number of LN obtained and related to general and disease free survival were studied.

Expected results:

To analyze the survival rate between patients Complete Pathologic Response with less than 12 LN and 12 or more LN. To determine the difference in survival between patients with less than 12 LN in complete versus incomplete response. Demonstrate that patients with complete pathologic response and less than 12 LN have a disease-free survival equal to or better than patients with 12 LN or more.

Inclusion Criteria: Patients with a biopsy-proven mid and low rectal adenocarcinoma located within 10 cm from the anal verge, stage cT3-4N0M0 or cT (any)N + M0, and patients with low (< 5 cm from anal verge) cT2N0 of distal rectum because of the risk of needing an abdominoperineal resection.

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Exclusion Criteria: Patients with synchronous colorectal cancer or other non-colorectal cancers, stage IV disease, rectal cancer in the setting of inflammatory bowel disease or familial adenomatous polyposis, palliative resections, previous pelvic radiotherapy, significant comorbidities that prevent curative surgical resection and/or CRT, concurrent participation in another research protocol involving therapeutic intervention

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Patients with mid and low rectal cancer within 10 cm from the anal verge, stage cT3-4N0M0 or cT (any)N + M0