New evidence suggests that patients with KRAS, BRAF or PTEN mutations experience fewer clinical responses to these drugs, compared with patients with wild-type tumours; moreover, molecular analysis, particularly of KRAS, is routinely being performed in standard molecular pathology laboratories (Lievre et al, 2006; Amado et al, 2008; Di Nicolantonio et al, 2008; Karapetis et al, 2008; Au et al, 2009; Jimeno et al, 2009; Sartore-Bianchi et al, 2009). This evidence concerns the gene BRAF and neoplasm.