NRAS and neoplasm: EGFR-I administration is now restricted to patients with RAS WT tumours, following retrospective analyses that initially demonstrated lack of mutation in KRAS exon 2 (codons 12 and 13) as a positive predictive marker [4, 5], with subsequent extension of predictive molecular markers to include other exons of KRAS as well as of NRAS (exons 2, 3, 4) [6–8].