When a person is diagnosed with colorectal cancer, their tumor tissue is often screened to see if their cancer was caused by Lynch syndrome. In some cases, when a woman is diagnosed with uterine (endometrial) cancer, her tumor tissue may be screened as well. The tumor tissue used for screening comes from tissue removed during a biopsy or surgery.
There are two types of Lynch syndrome tumor screening: Immunohistochemistry (IHC) and microsatellite instability (MSI) testing.
Not everyone with an abnormal IHC or MSI result will have Lynch syndrome, and additional testing may be necessary if a tumor screens positive. Genetic counseling and genetic testing for Lynch syndrome may be recommended if your tumor screening results are abnormal. If you are unsure whether or not your tumor has been checked for Lynch syndrome, talk to your doctor.