In colorectal cancer patients, AREG expression in particular has been repeatedly associated with an enhanced responsiveness to cetuximab, especially for KRAS wild-type tumours (Baker et al. 2011; Jacobs et al. 2009; Khambata-Ford et al. 2007; Pentheroudakis et al. 2013; Yoshida et al. 2013). This evidence concerns the gene KRAS and colorectal cancer.