Metastatic CRC patients with tumours harbouring a KRAS mutation are resistant to treatment with anti-EGFR antibodies, showing lower response rates, decreased progression-free survival, and overall survival compared with patients with KRAS wild-type tumours (Karapetis et al, 2008; Tol et al, 2009; Van Cutsem et al, 2009). This evidence concerns the gene KRAS and colorectal carcinoma.