KRAS and colorectal cancer: Current guidelines recommend dMMR screening for all colorectal cancer patients to identify a potential Lynch syndrome and the patients to benefit from further counseling and genetic testing.11–15 The screening can be done by using immunohistochemistry to evaluate the loss of protein expression16,17 or MSI testing to evaluate unstable microsatellite regions resulting from dMMR.18–20 KRAS also has a very important role in colorectal cancer.21