Preoperative Prediction Model of Pathological Outcomes (Mesorectum Quality and Positive Circumferential Resection Margin) in Patients With Mid-low Rectal Cancer

Study Overview
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Brief Summary
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Elaboration of a preoperative prediction model of the quality of the mesorectum and the involvement of the circumferential margin in patients with mid-low rectal cancer who undergo laparoscopic anterior rectal resection. In a second phase the investigators will study the utility of the prediction model in classifying patients with high risk of suboptimal quality of mesorectum and/or positive circumferential margin. Patients with high preoperative risk will undergo a transanal total mesorectal excision and patients with low risk a laparoscopic transabdominal mesorectal excision. The investigators finally will compare pathological outcomes ( quality of mesorectum and circumferential margin), survival and recurrence between the two groups.

Official Title
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Preoperative Prediction Model of Pathological Outcomes (Mesorectum Quality and Positive Circumferential Resection Margin) in Patients With Mid-low Rectal Cancer

Conditions
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Rectal Cancer

Intervention / Treatment
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* Procedure: Transanal total mesorectal excision of rectal cancer


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients directed to laparoscopic anterior rectal resection through a transabdominal or a transanal approach. Age ≥ 18 years Histology of adenocarcinoma or adenoma With or without neoadjuvant chemoradiotherapy TNM classification: T2 or T3, any N stage or M stage Intention of resection R0 Exclusion Criteria: TNM classification: T1 or T4. Complicated rectal cancer or emergency surgery. Previous major colorectal surgery

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| High risk patients<br>Patients with high risk of suboptimal mesorectum quality and/or positive circumferential margin after the application of the preoperative prediction model developed | Procedure: Transanal total mesorectal excision of rectal cancer<br>* To perform a total mesorectal excision through a transanal approach<br>|
| Low risk patients<br>Patients with low risk of suboptimal mesorectum quality and/or positive circumferential margin after the application of the preoperative prediction model developed | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Evaluation of the quality of mesorectum in the rectal specimen according to international consensus (goog quality, moderate quality and poor quality) | Evaluation of the quality of mesorectum as optimal or suboptimal (international consensus defines three grades of resection: Group 1: including mesorectal resection, good quality Group 2: intramesorectal resection: moderate quality Group 3: resection in the muscularis propria, poor quality). Investigators will group patients into two groups: optimal mesorectum (group 1) and suboptimal mesorectum (group 2-3). | 30 days | 
| Evaluation of the circumferential margin status in the rectal specimen according international consensus (positive margin if tumor ≤ 1mm from circumferential margin) | Evaluation of the circumferential margin status (positive or negative) in the rectal specimen according international consensus (positive margin if tumor ≤ 1mm from circumferential margin) | 30 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Recurrence | Rate of tumor recurrence | 2 years | 
| Survival | Rate of survival | 2 years |