Practical Molecular Pathology: Colon Cancer
The molecular diagnostics of colorectal cancer has important clinical implications for the detection of Lynch syndrome and for treatment of colorectal cancer. Detection of mismatch repair deficiency, either by PCR or immunohistochemistry, is the current first step in the Lynch syndrome tissue work-up. Subsequent evaluation of BRAF mutation status and MLH1 methylation help assess whether a mismatch repair deficient tumor is sporadic or potentially Lynch-associated. Mismatch repair deficiency is also associated with a good prognosis and a response to immunotherapy. Finally, evaluation of the EGFR pathway, in particular mutations in KRAS and NRAS, is useful to determine the potential efficacy of therapy with EGFR inhibitors.
