KRAS and colorectal carcinoma: 10. In their study, the discordance rate of KRAS mutational status between primary and paired metastases other than the lung was 12.3%, similarly to what we have previously reported 34, while it increased in the case of lung metastases reaching a rate of 32.4% 10. We did not analyze some of the mutations comprised in the RAS pathway, namely KRAS exon 4 and NRAS mutations that account for up to 9% of the mutations detected in the RAS pathway 9, 35. As a matter of fact, our analysis had been performed before the data on the role of KRAS exon 4 and NRAS mutations in CRC became available.