KRAS and colorectal carcinoma: The absence of activating Kirsten rat sarcoma viral oncogene (KRAS) and neuroblastoma RAS viral oncogene homolog (NRAS) mutations is confirmed prior to commencing antiEGFR (antiepidermal growth factor receptor) monoclonal antibody in advanced CRC 6, 7, 8, 9 due to the negative predictive effect of these mutation; however, most wildtype patients still show no significant response to these agents.