KRAS and colorectal carcinoma: The mutation frequencies of genes which served as resistant biomarkers for anti-EGFR monoclonal antibodies, including KRAS (50.3% in EO mCRC versus 56.4% in AO mCRC, p = 0.32), NRAS (6.1% in EO mCRC versus 5.5% in AO mCRC, p = 1), BRAF (10.9% in EO CRC versus 4.5% in AO CRC, p = 0.056), and PIK3CA (13.3% in EO CRC versus 12.7% in AO CRC, p = 1) were comparable between the two cohorts.