Somatic Mutations of K-Ras and BRAF in Thai Colorectal Cancer and their Prognostic Value


Background: The study aimed to determine the incidence of K-ras and BRAF mutations in colorectal cancers(CRCs) in Thai patients and evaluate association with clinicopathological parameters including treatmentoutcomes in terms of event free survival (EFS). Materials and
Methods: Two-hundred colorectal cancer specimenswere collected for studies of K-Ras codon 12, 13 and 61, and BRAF codon 600 by polymerase chain reaction anddirect nucleotide sequencing.
Results: The overall incidence of K-Ras mutations in our patients was 23%. K-rasmutation frequencies in CRC stages (AJCC) I, II, III and IV were 6.7%, 16.1%, 23.3% and 26.6%, respectively(p-value>0.05). The three most common mutation forms were G12D, G12V and G13D. K-Ras mutation status wasassociated with poorer EFS in stage I-III CRCs (p-value 0.03).
Conclusions: The study found a lower mutationfrequency of K-Ras and BRAF compared to reports involving other ethnic groups. However, K-Ras mutationsdid have a negative prognostic value in early-stage CRCs.