InterpretationThe epidermal growth factor receptor (EGFR) is a cell surface receptor belonging to the ErbB family tyrosine kinase receptors. EGFR is involved in cell growth control through its role in the two main intracellular pathways, the mitogen-activated protein kinase (MAPK) pathway and the phosphatidylinositol 3-kinase- (PI3K-) protein kinase B (AKT) pathway. The over-expression or mutation of EGFR may be responsible for the constitutive activation of these pathways. In colorectal cancer, EGFR has been found to be frequently over expressed, and may be associated with tumor stage and prognosis. Somatic EGFR mutations are infrequent in colorectal cancers. The frequency of EGFR mutations in colorectal cancer varies from 0.34 to 3.3% in Western population, and from 12% to 22.4% in Asians. In a subset of patients with EGFR mutations in colorectal cancer, the addition of anti-EGFR monoclonal antibodies to the conventional chemotherapeutic regimens may expand response rates and increase progression-free survival. EGFR V765M lies within the protein kinase domain of the protein. In lung cancer, the V765M has been reported as a sensitizing mutation to EGFR tyrosine kinase inhibitors. The correlation of EGFR gene mutations with clinicopathologic characteristics in colorectal cancers continues to be explored.