Biomarker analysis of cetuximab in colorectal cancer has identified potential biomarkers such as EGFR gene amplification and K-ras mutations that may guide treatment decisions (Moroni et al, 2005; Khambata-Ford et al, 2007; Sartore-Bianchi et al, 2007; Zhang et al, 2007; Bokemeyer et al, 2008; Cappuzzo et al, 2008; Lievre et al, 2008; Van Cutsem et al, 2008; Tejpar et al, 2008b). This evidence concerns the gene KRAS and colorectal cancer.