Site-Specific Factor 5

Microsatellite Instability


**Note:** The microsatellite instability (MSI) test is a genetic test performed on tumor tissue to look for differences in length of certain non-functioning sections of deoxyribonucleic acid (DNA). The differences are caused by problems with the genes that normally repair DNA. * A high-positive MSI (MSI-H) result may indicate that the gene repair problem is related to the development of the cancer, and that the patient may have hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome * A low-positive or stable MSI result (stable meaning that there are no differences in the lengths) means it is unlikely that the cancer is related to a hereditary condition




NAACCR #2920
Code Description
020 Microsatellite instability (MSI) stable; no MSI
040 MSI unstable low; positive, low
050 MSI unstable high; positive, high
060 MSI unstable, NOS; positive, NOS
988 Not applicable: Information not collected for this case
997 Test ordered, results not in chart
998 Test not done (test not ordered and not performed)
999 Unknown or no information
Not documented in patient record