Microsatellite Instability in Colorectal Cancer Prognosis
Summary
Microsatellite instability (MSI) arises when errors in short repetitive DNA sequences accumulate owing to defective DNA mismatch repair (MMR). In colorectal cancer (CRC), MSI occurs in approximately 10–20 per cent of tumours and identifies a distinct biological subgroup. These tumours often harbour frameshift mutations in key regulatory genes and are enriched for immune infiltration. Clinically, MSI-high CRCs tend to present at earlier stages, exhibit improved relapse-free and overall survival compared with microsatellite-stable counterparts, and show reduced benefit from fluoropyrimidine monotherapy. MSI status also predicts responsiveness to immune checkpoint blockade in advanced disease, making it a cornerstone of therapeutic decision-making and patient stratification. Testing for MSI and MMR protein expression is now recommended universally for newly diagnosed CRC, both to detect Lynch syndrome and to guide adjuvant and systemic treatment choices. Despite the generally favourable outlook, the prognostic advantage may diminish in more advanced stages, and optimal chemotherapy regimens for MSI-high tumours remain under active investigation.
Research from Nature Portfolio
A multicentre cohort study of colon cancer patients with deficient MMR assessed the timing and composition of adjuvant chemotherapy. While stage I and high-risk stage II patients showed no significant overall survival benefit from postoperative chemotherapy, stage III and IV patients experienced a clear survival advantage when treated with oxaliplatin-containing regimens. Notably, initiating oxaliplatin‐based therapy early after surgery was associated with the greatest improvement in outcomes. These findings refine the role of adjuvant chemotherapy in MMR-deficient CRC and support early commencement of combination regimens in higher-stage disease.
Microsatellite Instability in Colorectal Cancer Prognosis publication trend
The graph below shows the total number of articles in microsatellite instability in colorectal cancer prognosis across all publications each year (not limited to Nature Index journals).
Technical terms
Microsatellite instability (MSI): A condition in which short repetitive DNA sequences become hypermutable due to impaired mismatch repair.
DNA mismatch repair (MMR): A cellular mechanism that recognises and corrects base-pairing errors during DNA replication.
Deficient mismatch repair (dMMR): Loss of function in MMR proteins, leading to increased mutation rates and microsatellite instability.
Lynch syndrome: A hereditary cancer predisposition caused by germline mutations in MMR genes, notably MLH1, MSH2, MSH6 or PMS2.
Relapse-free survival (RFS): The length of time after primary treatment during which a patient remains free of disease recurrence.
References
- Single-cell AI-based detection and prognostic and predictive value of DNA mismatch repair deficiency in colorectal cancer. Cell Reports Medicine (2024).
- Mismatch Repair (MMR) Gene Mutation Carriers Have Favorable Outcome in Colorectal and Endometrial Cancer: A Prospective Cohort Study. Cancers (2024).
- Stage III deficient mismatch repair colon patients get greater benefit from earlier starting oxaliplatin-based chemotherapy regimen. Scientific Reports (2023).
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