In a series of 48 CRC patients, an overall concordance of 92% was observed between primary tumours and metastases for the presence of mutations within KRAS exon 2 and BRAF exon 5 (Artale et al, 2008); however, in the specific subgroup of patients with KRAS mutation, 23% of discordance was observed between the two tumour sites. The gene discussed is KRAS; the disease is neoplasm.