Predictive Value of DNA Mismatch Repair System in Colorectal Cancers

Study Overview
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Brief Summary
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Microsatellite instable (MSI) tumors represent almost the 15% of all sporadic colorectal cancers (CRCs). Literature data show that this unique tumor population appears to be poorly responsive to conventional chemotherapy and conversely reveals excellent results to immunotherapy. Our data, as demonstrated by propensity score-matched and win ratio analysis, show that there are no substantial differences between MSI and MSS tumors in early CRC stages treated with surgery alone. On the contrary, stable tumors (MSS) did much better than MSI tumors in advanced CRC stages undergoing conventional adjuvant treatment. Determination of status of DNA mismatch repair system is crucial in high-risk CRCs to optimize treatment.

Detailed Description
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Colorectal cancers (CRCs) with deficient DNA mismatch repair (MMR) system (so called dMMR or MSI tumors) represent a no-negligible part of sporadic CRCs. Prognostic value of this unique cell population remains controversial, but undoubtedly these tumors are characterized by poor response to conventional chemotherapy, an high tumor mutational burden resulting in a brisk immuno response, and, as recently observed, excellent results to the immunotherapy. The aim of this study was to evaluate, by using sophisticated statistical analyses, the predictive value of MSI status and its optimal treatment. A series of 403 consecutive CRC patients treated by the same oncological team from 2014 to 2021 entered the study. No patients underwent immunotherapy. Immunohistochemistry, integrated by polymerase chain reaction if appropriate, was used to categorize specimens in microsatellite stable (MSS) and instable (MSI) tumors. The win ratio (WR) approach was utilized to compare composite outcomes of MSS and MSI tumors while controlling for radical versus no radical resection, propensity score-matched analysis, and reversing primary endpoint.

Official Title
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Assessment of the DNA Mismatch Repair System is Crucial in Colorectal Cancers Necessitating Adjuvant Treatment: a Propensity Score-matched and Win Ratio Analysis

Conditions
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MSI-H Colorectal Cancer

Intervention / Treatment
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* Procedure: colorectal resection


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: all consecutive CRC patients observed from January 2014 to December 2021 Exclusion Criteria: Patients with suspected or confirmed Lynch's syndrome (12 patients) and rectal cancers (98 patients) undergoing neoadjuvant treatment

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 86 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 |
| --- | --- |
| group 1 or MSS<br>colorectal cancers (CRCs) with stable microsatellite | Procedure: colorectal resection<br>* potential resective surgery<br>|
| group 2 or MSI<br>colorectal cancers (CRCs) with unstable microsatellite | Procedure: colorectal resection<br>* potential resective surgery<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| survival rate | overall survival | From date of surgical operation until the date of death from any cause assessed up to 60 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| recurrence rate | disease-free survival | From date of surgical operation until the date of documented tumor recurrence assessed up to 60 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Colorectal cancers;, DNA mismatch repair;, Win ratio