Interval Between Neoadjuvant Therapy and Surgery in the Treatment of Locally Advanced Rectal Cancer (CRONOS)

Study Overview
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Brief Summary
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The investigators evaluate the response of rectal cancer to neoadjuvant therapy and classify the response according to specific periods of time after the end of neoadjuvant treatment.

Detailed Description
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In the treatment of locally advanced rectal cancer, an optimal interval between neoadjuvant therapy and surgery might improve oncological outcomes. Besides, those patients who achieve a good response might benefit from active surveillance, avoiding surgical comorbidities. This optimal interval is yet to be defined. This study will aim to better define the role of time interval between the end of neoadjuvant therapy (NAT) and TME in Spanish regions, together with analyzing the importance of restaging MRI and define the basis for implementing a watch and wait protocol.

Official Title
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Interval Between Neoadjuvant Therapy and Surgery in the Treatment of Locally Advanced Rectal Cancer

Conditions
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Rectal Cancer, Neoadjuvant Therapy

Intervention / Treatment
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* Procedure: Interval between NAT and surgery


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients suitable for elective surgical resection of biopsy-confirmed rectal adenocarcinoma (0-15 cm from the anal verge) determined by rectal cancer protocol magnetic resonance imaging. Patients treated with long-course neoadjuvant chemoradiotherapy (nCRT). Patients treated with short-course radiotherapy with delayed surgery. Clinical stage IIA, IIB, IIIA, IIIB, IIIC (cT3/cT4, or cN1/cN2 with any cT, M0) determined by rectal cancer protocol magnetic resonance imaging Exclusion Criteria: Intolerance or contraindication to planned NAT. Patients who have not finished NAT for any reason. Patients with unknown cT or cM. Tumors previously treated with local excision or with distant metastatic disease.
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 |
| --- | --- |
| Short interval group<br>≤ 8weeks between the end of neoadjuvant therapy and surgery | Procedure: Interval between NAT and surgery<br>* Evaluate three groups according to the interval between the end of neoadjuvant therapy and surgery.<br>|
| Intermediate interval group<br>> 8 and ≤ 12 weeks between the end of neoadjuvant therapy and surgery | Procedure: Interval between NAT and surgery<br>* Evaluate three groups according to the interval between the end of neoadjuvant therapy and surgery.<br>|
| Long interval group<br>> 12 weeks between the end of neoadjuvant therapy and surgery | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pathological response | Grade as complete | 2000-2019 | 
| Circumferential margin (CRM) | Described as free (CRM >1 mm) | 2000-2019 | 
| Distal resection margin (DRM) | Described as free (DRM >1 mm) | 2000-2019 | 
| Quality of the specimen | Described as complete or incomplete | 2000-2019 |