Microsatellite Instability Analysis

One paraffin-embedded tumor and either whole blood or paraffin-embedded normal tissue

Eight unstained slides at 5 μM and one matching H&E slide or FFPE tissue block or 3-5 mL whole blood

Samples with ≥4 mm² tumor and normal tissue surface area and ≥50% tumor content are preferred; 3 mL whole blood

FFPE tissue block or slides, lavender-top (EDTA) tube or green-top (sodium heparin) tube, tan-top (K2-EDTA) tube or pink-top (K2-EDTA) tube

Blocks and slides at room temperature; whole blood at 2°C to 8°C

Tumor block containing insufficient tumor tissue or no tumor; broken or stained slides. 

Whole blood: Contaminated specimen; frozen whole blood received; leaking tube; clotted blood; hemolysis; specimen containing suspicious foreign material; quantity not sufficient for analysis

This test is used to identify tumors with microsatellite instability. High-frequency microsatellite instability (MSI-H) is associated with Lynch syndrome, but it is also found in 15% to 20% of sporadic colorectal and endometrial cancers. Lynch syndrome is an autosomal-dominant inherited cancer syndrome that predisposes to colorectal, endometrial, gastric, ovarian, upper urinary tract and other cancers. MSI-H status may enhance the likelihood of tumor responsiveness to immune checkpoint inhibitor therapy.

MSI-H is a marker of underlying DNA mismatch repair defect but does not define specific gene mutations responsible for cancers. If direct testing for gene mutations responsible for Lynch syndrome is desired, please call customer service at 800-345-4363 for more information. This assay can detect 8% to 12% of mutant in a background of wild-type genomic DNA.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Multiplex polymerase chain reaction (PCR); capillary electrophoresis