Combination therapy comprising anti-epidermal growth factor receptor (EGFR) antibody and anti-cytotoxic drugs has shown a survival benefit as a first-line [1], as well as a second-, third-, and salvage-line chemotherapy [2–7] for patients with metastatic colorectal cancer (mCRC) without RAS mutations. This evidence concerns the gene EGFR and metastatic colorectal cancer.