Microsatellite Instability Testing and Prognostic Implications in Colorectal Cancer

Area of Science:

• Oncology
• Molecular Diagnostics
• Cancer Genomics

Background:

• Microsatellite instability (MSI) is a critical predictive biomarker in colorectal cancer (CRC).
• Current MSI screening methods include immunohistochemistry (IHC) and PCR-based assays.
• There is a need for accurate and reliable MSI detection methods for prognostic assessment in CRC.

Purpose of the Study:

• To compare the diagnostic accuracy of droplet digital PCR (ddPCR) MSI assay with IHC.
• To evaluate the prognostic significance of ddPCR-based MSI in colorectal cancer (CRC).
• To identify clinicopathological features associated with CRC patient outcomes.

Main Methods:

• Analyzed formalin-fixed paraffin-embedded tumor samples from 48 CRC patients.
• Compared MSI results from IHC and ddPCR using Cohen's kappa measurement.
• Performed Kaplan-Meier survival analyses and Cox regression for prognostic assessment.

Main Results:

• High agreement was observed between ddPCR and IHC for MSI detection (k = 0.915).
• MSI-high CRC patients demonstrated significantly better overall survival (OS) and disease-free survival (DFS).
• Right-sided MSI-high CRC patients showed improved DFS, while left-sided CRC patients did not exhibit this benefit.

Conclusions:

• Droplet digital PCR (ddPCR) is a promising and accurate tool for MSI detection in colorectal cancer (CRC).
• MSI-high status is a favorable prognostic marker for CRC patients, particularly for right-sided tumors.
• Combined use of ddPCR and IHC may offer complementary prognostic information for CRC management.