KRAS and BRAF mutations in Serbian patients with colorectal cancer.

Objective: Mutations of KRAS and BRAF genes represent molecular biomarkers of response to targeted therapy in patients with metastatic colorectal cancer (mCRC). Since these mutations have been shown to exert different biological effects and impacts on patients' outcome, there is a need to determine reliably the frequency and types of KRAS mutations for diagnostic and individual therapeutic purposes. Despite having a wild type (wt) KRAS, some patients fail to respond to treatment. BRAF V600E mutation is an additional molecular determinant of response to the same therapy. In this study we described the KRAS and the BRAF V600E mutation spectra and frequencies in a group of Serbian mCRC specimens.

Methods: KRAS mutations were determined with DxS TheraScreen® K-RAS Mutation Kit and KRAS StripAssay(™), and for the BRAF V600E mutation we applied High Resolution Melting (HRM) analysis.

Results: KRAS mutations were present in 34.7% of 190 analyzed samples. The 7 most frequent mutation types observed were: G12D 43.9%, G12V 21.2%, G12A 10.6%, G12C 7.6%, G12S 4.5%, G12R 1.5%, G13D 10.6%. Among the wt KRAS patients, 17.8% carried the BRAF V600E mutation.

Conclusions: We have shown that the spectrum and frequency distribution of the identified KRAS and BRAF mutations in Serbian study population are in good accordance with literature data. We believe that our results are significant concerning aspects related to tumor molecular biology as well as to patient selection in the diagnostic settings.