Mutations in the Kirsten Ras (KRAS) oncogene occur in 30–40% of colorectal cancers (CRCs) and have been associated with poor prognosis and resistance to anti-epidermal growth factor receptor (EGFR)-targeted cancer therapy (Andreyev et al. 2001; Arrington et al. 2012; Misale et al. 2014, 2012; Phipps et al. 2013; Tougeron et al. 2013) such as the monoclonal antibody panitumumab. This evidence concerns the gene KRAS and colorectal cancer.