Clinical Characteristics of Colorectal Cancer in Patients With Egfr-Signaling Pathway Gene Mutations

Abstract

KRAS, NRAS, BRAF mutations are associated with an unfavorable prognosis for colorectal cancer (CRC). At the same time, there is no single point of view on disease development during adjuvant chemotherapy (ACT). Objective. The authors aimed at studying KRAS, NRAS and BRAF mutations in the tumor and their influence on the clinical characteristics of colorectal cancer development. Materials and Methods. Paraffin blocks of the primary CRC tumor (n=37) were used as the material for the study. Using genomic DNA, isolated from the primary tumor, real-time PCR was used to determine the most common mutations in CRC: KRAS gene (exon 2, codon region 12–13), NRAS gene (exon 3, codon region 61), B6F V600E gene. Results. The results of genotyping of DNA samples isolated from the primary CRC tumor paraffin blocks showed that BRAF gene mutations were detected in 8.2 % of cases, NRAS gene mutations were detected in 5.4 % of cases, and KRAS gene mutations were detected in 37.8 % of cases. The authors didn’t reveal any dependencies of the mutation distribution on patients’ gender and age. The examined mutations were more common in adenocarcinomas of high and moderate degrees of differentiation. The relapse-free period after ACT in patients with identified KRAS, NRAS, BRAF gene mutations is significantly less than in those without mutations. Conclusion. The findings suggest that EGFR signaling pathway mutations (KRAS, NRAS and BRAF) increase the risk of disease recurrence and are an unfavorable prognostic factor. Keywords: colorectal cancer, NRAS, KRAS, BRAF mutations, adjuvant chemotherapy.