A SIMPLE METHOD FOR DETECTION OF KRAS AND BRAF HOTSPOTS MUTATIONS IN PATIENTS WITH COLORECTAL CANCER

Objective: Accurate mutation detection assays for KRAS and BRAF genes in colorectal cancer are strongly needed. We describe a simple and reliable technique for determination of KRAS and BRAF mutational status, and we estimate the KRAS and BRAF mutations frequency in Moroccan patients with colorectal cancer. Methods: Forty-seven samples from patients with metastasic colorectal adenocarcinomas were studied for BRAF exon 15 and KRAS codons 12 and 13 mutations. Tumor tissue was removed by manual macrodissection from formalin-fixed paraffin-embedded tissues specimens. After DNA extraction, conventional PCR was performed and the DNA was analyzed by direct sequencing. Results: KRAS codon 12 or 13 mutations were present in 51% of patients. Gly12Val mutation was present in 21% of all patients, Gly12Asp in 15%, Gly13Asp in 6%, Gly12Arg in 4%, Gly12Cys in 2% and Gly12Ala in 2%. No BRAF mutation was detected. Conclusion: Our data suggest that KRAS mutations are more frequent than BRAF mutations in Moroccan patients with colorectal carcinomas. To our knowledge, we are the first to report such a high proportion (more than 50%) of potentially non responsive patients for the anti-EGFR treatment in Morocco. These results show that the method we used was accurate, cost-effective and time-efficient.