KRAS mutations have been widely investigated to be a major predictive biomarker for resistance to EGFR blockade in patients with mCRC.3 In addition to the most common mutations in codons 12 (Gly12Ala, Gly12Arg, Gly12Asp, Gly12Cys, Gly12Ser, and Gly12Val) and 13 (Gly13Asp) in exon 2, KRAS mutations are also found in exon 3 (codons 59 and 61) and exon 4 (codons 117 and 146) in CRC patients. This evidence concerns the gene KRAS and colorectal carcinoma.