Currently, there is no prediction scale available to identify patients with rectal neoplasms as technically complex in the middle and lower thirds; that is, those who are at high risk of affected circumferential margins and low quality of the mesorectum. The application of a predictive model that allows preoperative identification of the group of patients in whom optimal results in mesorectal quality and circumferential margin are less likely to be obtained through laparoscopic or minimally invasive surgery would enable the selection of patients who will require and justify all efforts and healthcare resources to improve surgical outcomes.

Therefore, the investigators aim to create a predictive model to identify these patients, allowing the discrimination of which patients will benefit from different techniques, or even which ones would be opportune to initially consider an open approach.

Inclusion Criteria:

• Scheduled surgery for anterior resection of the rectum meeting oncological criteria with mesorectal excision.
• Age ≥ 18 years.
• Histology of adenocarcinoma with or without neoadjuvant chemotherapy or chemoradiotherapy.
• Initial stage T1-T4a. Any N. Any M.
• Intention for R0 resection.

Exclusion Criteria:

• Colorectal tumor with histology different from adenocarcinoma.
• Synchronous colon tumor.
• Benign pathology or adenoma.
• Tis.
• T4b or oncological multivisceral resections.
• History of neoplastic colorectal surgery or local excision or TAMIS.
• Perforated or obstructive rectal neoplasm.

Patients diagnosed with rectal neoplasia undergoing elective surgery during a period of time from 2017 to 2021