Journal Article


D C Winter
H M Mohan
B Creavin
K Sheahan
E Ryan


Medicine & Nursing

mismatch repair testing current colorectal cancer crc polymerase chain reaction genetic testing colorectal cancer microsatellite instability

The current value of determining the mismatch repair status of colorectal cancer: A rationale for routine testing. (2016)

Abstract Colorectal Cancer (CRC) is the third most prevalent cancer in men and women. Up to 15% of CRCs display microsatellite instability (MSI). MSI is reflective of a deficient mismatch repair (MMR) system and is most commonly caused by hypermethylation of the MLH1 promoter. However, it may also be due to autosomal dominant constitutional mutations in DNA MMR, termed Lynch Syndrome. MSI may be diagnosed via polymerase chain reaction (PCR) or alternatively, immunohistochemistry (IHC) can identify MMR deficiency (dMMR). Many institutions now advocate universal tumor screening of CRC via either PCR for MSI or IHC for dMMR to guide Lynch Syndrome testing. The association of sporadic MSI with methylation of the MLH1 promoter and an activating BRAF mutation may offer further exclusion criteria for genetic testing. Aside from screening for Lynch syndrome, MMR testing is important because of its prognostic and therapeutic implications. Several studies have shown MSI CRCs exhibit different clinicopathological features and prognosis compared to microsatellite-stable (MSS) CRCs. For example, response to conventional chemotherapy has been reported to be less in MSI tumours. More recently, MSI tumours have been shown to be responsive to immune-checkpoint inhibition providing a novel therapeutic strategy. This provides a rationale for routine testing for MSI or dMMR in CRC.
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Full list of authors on original publication

D C Winter, H M Mohan, B Creavin, K Sheahan, E Ryan

Experts in our system

Desmond C. Winter
University College Dublin
Total Publications: 53
Helen M Mohan
University College Dublin
Kieran Sheahan
University College Dublin
Total Publications: 40
Elizabeth J Ryan
University College Dublin