Multiple mutations in the Kras gene in colorectal cancer: review of the literature with two case reports

Purpose Kras mutations are negative predictors of anti-EGFR therapy, occurring in 40% of colorectal carcinomas (CRCs). Point substitutions in codon 12 or 13 are the most frequent mutations in Kras, but multiple mutations (MMs) in other codons can also develop. Few data exist on MMs with regard to their frequency and the codons and amino acids that are affected. We report two cases of Kras double mutations in codons 12 and 13 and review Kras MMs in primary CRC in PubMed databases.