KRAS and colorectal cancer: Retrospective‐prospective approaches have been a mainstay approach, for example with KRAS (De Roock et al., 2010; Catenacci et al., 2011c) (and now NRAS (Douillard et al., 2013, 2013)) mutations demonstrating lack of benefit of anti‐EGFR monoclonal antibody therapies in colorectal cancer (Figure 4A).