Mutation pattern of KRAS and BRAF oncogenes in colorectal cancer patients.

The aim of this study was to identify KRAS and BRAF gene mutations in colorectal cancer patients and to assess whether they are linked with clinicopathological features. The results of KRAS and BRAF mutation analysis could be used in the selection of patients for anti-EGFR therapy. All specimens were obtained during routine surgery of patients with colorectal carcinoma. The diagnoses were established by standard procedures and confirmed histopathologically. After DNA extraction, KRAS mutations were analyzed using quantitative real-time PCR and BRAF mutations were analyzed using real-time PCR by fluorescence melting curve analysis. Our results show that KRAS gene mutations were detected in 35.6% samples and the most frequent mutation was Gly12Val. BRAF gene mutation Val600Glu was detected in 8.5% samples. Statistical analysis revealed a significant association between the KRAS mutation and Dukes' stage (p=0.034), with the lowest frequency in Dukes'A, and between the KRAS mutation and histological grade (p=0.044), with no KRAS mutation found in poor differentiated tumors. The first data about KRAS and BRAF mutational status in the sample of Croatian population with colorectal cancer shows that the incidence of KRAS and BRAF mutations is within generally valid limits. Prospective studies are to be continued in order to determine whether these mutations contribute to progression of colorectal cancer.