TKRCD-MSI Study: Current Microsatellite Stability Findings in Colon Cancer - Nationwide Experience From Turkey
Trial Snapshot
- Phase
- Not Applicable
- Status
- Not yet recruiting
- Sponsor
- Enrollment
- 1,500
- Locations
- 2
- Primary Endpoint
- Prevalence and Anatomical Distribution of dMMR in Colon Cancer in Turkey
Study Overview
Brief Summary
The goal of this prospective observational study is to learn more about how a specific type of DNA repair issue-called mismatch repair deficiency (dMMR)-affects colon cancer in people living in Turkey. The study will look at how often dMMR occurs, how it is reported, and how it relates to treatment outcomes.
The main questions it aims to answer are:
- How common is dMMR in colon cancer, and does it vary by where the tumor is in the colon?
- How often is MSI (microsatellite instability) status reported in colon cancer biopsy reports before surgery?
- How do different types of dMMR (such as MLH1/PMS2 loss, MSH2/MSH6 loss, or sporadic cases) affect survival over three years?
Participants will:
- Be people who had surgery for colon cancer between June 1, 2025 and May 31, 2026 at hospitals in Turkey that treat more than 30 colon cancer cases each year.
- Have their medical and pathology data reviewed, including information about tumor location, biopsy results, surgery, and treatment.
This study will not involve any new treatments. Instead, it will use existing medical records to better understand how to improve care and identify people who may benefit from immunotherapy. Results from this study will be shared at scientific meetings and published in medical journals.
Detailed Description
This is a prospective, multicenter observational study designed to evaluate the distribution and clinical relevance of microsatellite instability (MSI) and mismatch repair (MMR) subtypes in patients undergoing curative colon cancer surgery across Turkey. The study will run between June 1, 2025, and May 31, 2026, and is being conducted to address gaps in national data on MSI frequency and subtype patterns, which have critical prognostic and therapeutic implications.
Mismatch repair deficiency (dMMR) leads to genetic instability and is commonly associated with high levels of microsatellite instability (MSI-H). This condition results from the loss of expression in key MMR proteins-MLH1, PMS2, MSH2, and MSH6-and is linked to distinct tumor behaviors, including:
- Improved overall survival compared to MMR-proficient tumors
- Reduced risk of nodal and distant metastases
- Increased resistance to 5-fluorouracil (5-FU) and potential sensitivity to oxaliplatin
- Favorable response to immune checkpoint inhibitors, including neoadjuvant immunotherapy in selected patients with MSI-H/dMMR tumors
The primary objective of this study is to determine the prevalence and anatomical distribution of dMMR in colon cancer.
The secondary objective is to assess how frequently MSI status is reported in preoperative endoscopic biopsies.
Study Design
- Study Type
- Observational
- Observational Model
- Cohort
- Time Perspective
- Prospective
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •Patients who have undergone curative-intent surgery for colon adenocarcinoma between June 1, 2025, and May 31, 2026 Surgery performed at a center with >30 colon cancer surgeries per year Availability of MMR protein immunohistochemistry (IHC) and/or MSI test results from resection specimen and/or preoperative endoscopic biopsy Signed informed consent for participation and data collection
Exclusion Criteria
- •Non-adenocarcinoma malignancies of the colon (e.g., neuroendocrine tumors, lymphomas) Rectal cancers (defined as tumors within 15 cm of the anal verge on endoscopy or MRI) Incomplete medical or pathological records preventing classification of MMR status
Outcomes
Primary Outcomes
Prevalence and Anatomical Distribution of dMMR in Colon Cancer in Turkey
Time Frame: Within 30 days post-operative based on final pathology report
The proportion of colon cancer patients with mismatch repair deficiency (dMMR), stratified by tumor location (right-sided vs left-sided colon). This will be determined using immunohistochemical analysis of MMR protein expression (MLH1, PMS2, MSH2, MSH6) in resection specimens.
Secondary Outcomes
- Frequency of MSI Reporting in Preoperative Endoscopic Biopsies(At time of initial diagnostic biopsy (baseline))
- Three-Year Disease-Free Survival (DFS) and Overall Survival Across MMR Subtypes(3 years from date of surgery)