Current Microsatellite Stability Results in Colon Cancer

NCT06971107 | Not Yet Recruiting DMC

• 1 other identifier: TKRCD-MSI
• Study Type: observational
• Target: 1,500
• Locations: 1 country
• Sites: 2

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.

Conditions

Colon Adenocarcinoma; MSI Positive Colorectal Cancer; MSI Negative Colorectal Cancer

Keywords

Colorectal Neoplasms; Microstaellite Instability; DNA Mismatch Repair; Immunohistochemistry; Prognosis; Survival Analysis; Epidemiologic Methods

Outcome Measures

Primary Outcomes (1)

• Prevalence and Anatomical Distribution of dMMR in Colon Cancer in Turkey

  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.

  Within 30 days post-operative based on final pathology report

Secondary Outcomes (2)

• 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

Study Arms (3)

MLH1/PMS2 loss group

Participants whose tumors show loss of MLH1 and PMS2 protein expression, typically associated with dMMR or MLH1 promoter hypermethylation. These tumors will be analyzed for clinical features and oncologic outcomes (DFS and OS) over 3 years.

MSH2/MSH6 Loss Group

Participants whose tumors show loss of MSH2 and MSH6 protein expression. This pattern is commonly associated with Lynch syndrome, a hereditary form of mismatch repair deficiency. Prognostic and treatment outcome data will be analyzed.

Sporadic Group (pMMR)

Participants with no loss of MMR protein expression (proficient MMR; pMMR). These cases represent sporadic tumors without mismatch repair deficiency and will serve as a comparison group for evaluating oncologic outcomes.

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Participants will be recruited from multiple high-volume general surgery centers across Turkey, including both public and private hospitals. The study will include institutions from major urban regions,as well as selected regional hospitals with established colorectal surgery programs.

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Turkish Society of Colon and Rectal Surgery: lead

Study Sites (2)

İstanbul Medipol University

Istanbul, Turkey (Türkiye)

Location

Koç University

Istanbul, Turkey (Türkiye)

Location

Related Publications (2)

• de Gooyer PGM, Verschoor YL, van den Dungen LDW, Balduzzi S, Marsman HA, Geukes Foppen MH, Grootscholten C, Dokter S, den Hartog AG, Verbeek WHM, Woensdregt K, van den Broek JJ, Oosterling SJ, Schumacher TN, Kuhlmann KFD, Beets-Tan RGH, Haanen JBAG, van Leerdam ME, van den Berg JG, Chalabi M. Neoadjuvant nivolumab and relatlimab in locally advanced MMR-deficient colon cancer: a phase 2 trial. Nat Med. 2024 Nov;30(11):3284-3290. doi: 10.1038/s41591-024-03250-w. Epub 2024 Sep 15.

  PMID: 39278994 BACKGROUND

• Anderson CE, Liska D. Treatment of Microsatellite-Unstable Rectal Cancer in Sporadic and Hereditary Settings. Clin Colon Rectal Surg. 2023 Aug 11;37(4):233-238. doi: 10.1055/s-0043-1770717. eCollection 2024 Jul.

  PMID: 38882941 BACKGROUND

MeSH Terms

Conditions

Colonic Neoplasms; Colorectal Neoplasms

Condition Hierarchy (Ancestors)

Intestinal Neoplasms; Gastrointestinal Neoplasms; Digestive System Neoplasms; Neoplasms by Site; Neoplasms; Digestive System Diseases; Gastrointestinal Diseases; Colonic Diseases; Intestinal Diseases; Rectal Diseases

Study Officials

• Ahmet Rencüzoğulları, Professor

  Koç University

  STUDY DIRECTOR

• Mustafa Öncel, Professor

  İstanbul Medipol University

  STUDY CHAIR

• Burak Yavuz, M.D.

  Republic of Türkiye Ministry of Health Kozan State Hospital

  PRINCIPAL INVESTIGATOR

• Atıf Tekin, M.D.

  İstanbul Medipol University

  PRINCIPAL INVESTIGATOR

• Cihangir Akyol, Professor

  Ankara University

  STUDY CHAIR

Central Study Contacts

Ahmet Rencüzoğulları, Professor

CONTACT

+90 532 179 82 80; arencuzogullari@ku.edu.tr

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 6, 2025
• First Posted: May 14, 2025
• Study Start: June 1, 2025
• Primary Completion (Estimated): May 31, 2026
• Study Completion (Estimated): May 31, 2029
• Last Updated: May 14, 2025

Record last verified: 2025-05

Data Sharing

• IPD Sharing: Will not share

Locations

TU (2)