Overview: Microsatellite Instability PCR TestIntroduction: The Microsatellite Instability PCR Test detects MSI to assess colorectal cancer risk, causing bleeding or pain. Aligned with 2023 NCCN guidelines, it uses PCR for high specificity, supporting cancer screening. This test is critical for guiding diagnosis, treatment planning, and improving outcomes in molecular pathology for patients with suspected colorectal cancer or Lynch syndrome.
Other Names: MSI PCR Assay, Colorectal Cancer Risk Test.
FDA Status: Laboratory-developed test (LDT), meeting molecular pathology standards for diagnostic accuracy.
Historical Milestone: MSI testing began in the 1990s with colorectal cancer research. PCR methods improved in the 2000s, enhancing diagnostic precision.
Purpose: Detects MSI to assess colorectal cancer risk, guides treatment, and evaluates patients with bleeding or pain.
Test Parameters: 1. Microsatellite Instability
Pretest Condition: No fasting required. Collect tissue, whole blood, or saliva. Report history of bleeding, pain, or colorectal cancer symptoms.
Specimen: Tissue (FFPE, 0.5-2 cma³), Whole Blood (EDTA, 2-5 mL), Saliva (sterile container, 1-2 mL). Transport in a biohazard container.
Sample Stability at Room Temperature: 7 days
Sample Stability at Refrigeration: Not refrigerated
Sample Stability at Frozen: Not frozen
Medical History: Document bleeding, pain, weight loss, or family history of colorectal cancer. Include current medications, especially chemotherapy.
Consent: Written consent required, detailing the tests purpose, colorectal cancer implications, and risks of sample collection.
Procedural Considerations: Uses PCR to detect MSI in specimens. Results are available in 3-5 days, supporting clinical decisions. Performed in laboratories, often for colorectal cancer risk assessment.
Factors Affecting Result Accuracy: Low DNA yield or improper sample storage can affect results. Contamination may reduce specificity.
Clinical Significance: High MSI suggests colorectal cancer or Lynch syndrome, guiding immunotherapy or genetic counseling. Stable MSI may require further testing.
Specialist Consultation: Consult an oncologist or geneticist for result interpretation and treatment planning.
Additional Supporting Tests: MMR immunohistochemistry, BRAF mutation testing, or colonoscopy to confirm colorectal cancer diagnosis.
Test Limitations: Not all colorectal cancers show MSI; clinical correlation is needed. Sample quality affects sensitivity.
References: NCCN Colorectal Cancer Guidelines, 2023; Journal of Clinical Oncology, Boland CR, 2022.
