MSI occurs in approximately 15% of CRC patients and more frequently in stage II (~20%) compared to stage III (~11%) and stage IV (~3.5%) CRCs. Nevertheless, MSI has also been observed in other types of cancer as shown in the following table.
|Breast||<%1, unless occuring in young women with HNPCC||-|
|Colorectal cancer||%15||All cancers|
|Endometrial||Up to %33'||40% of endometrioid tumours and 2% of serous tumours.|
|Glioma||%0-33||Controversial data. Pediatric, young adults|
|Head and Neck Cancer||None||-|
|Pancreatic and Periampullary||%1 in sporadic PDAC, %10 in cancers of periampullary area||All cancers|
|Prostate Cancer||Up to %12||Advanced stage cancers|
|Renal cell carcinoma||None||-|
|Sebaceous skin tumors||%25||All cancers|
The knowledge of the MSI status is valuable for:
- Determination of prognosis of Stage II Colon Cancer patients.
- Identification of patients with a higher risk of developing Hereditary Non Polyposis Colorectal Cancer (Lynch Syndrome).
- Identification of patients eligible for OncotypeDX® Colon.
- Prediction of 5-FU treatment.
- Response to immunotherapy.