MSI testing
Patients with clinical criteria or family history suggestive of HNPCC (Hereditary nonpolyposis colorectal cancer) can have a Microsatellite instability (MSI) test to investigate the possibility.
Microsatellite instability (MSI) – is a genetic condition that leads to a high predisposition to have mutations and the most common cause of colon cancer.
This type of test has some unique characteristics that you can learn more about here
MSI can be used in cases where there is a suspicion of HNPCC, but also as a complementary exam for the diagnosis of sporadic cancers (nonhereditary).
This is important because sporadic tumors positive for MSI tend to be more aggressive, and as a result, will need stronger therapies.
MSI positive cancers respond better as well to 5-fluorouracil (5-FU)-based chemotherapy.