Therefore, the aims of our study were: (1) to observe the relationship of AREG and EREG mRNA expressions between the primary site of colorectal cancer and the corresponding liver metastatic site, (2) determine whether the gene expression from the primary site or the liver metastatic site is more likely to be associated with clinical outcome, (3) determine the significance of AREG and EREG as a prognostic markers for patients who have not received anti-EGFR therapy, and see their relation to KRAS mutant status. The gene discussed is EREG; the disease is colorectal cancer.