Clinical significance of K-ras and BRAF mutations in Chinese colorectal cancer patients

Aim: To identify and assess mutations in the K-ras and BRAF genes in a cohort of Chinese patients with colorectal cancer (CRC) for their association with various clinicopathological parameters and prognosis.

Methods: Genomic DNA was isolated from frozen tissues. Pyrosequencing analysis was conducted to detect mutations in the K-ras (codons 12, 13, and 61) and BRAF genes (codon 600). Statistical analysis was carried out using SPSS-15.0 software.

Results: Among the 118 colorectal cancer patients, we detected 41 (34.7%) mutations in the K-ras gene. Mutation frequencies at codon 12 and codon 13 were 23.7% (28/118) and 10.2% (12/118), respectively. Only one patient harbored a point mutation at codon 61 (0.8%, 1/118). Gender was the only factor that showed an obvious relationship with K-ras gene mutation (female 44.7% vs male 28.2%, P = 0.037). Other clinicopathological features, such as age, location of the tumor, tumor differentiation, Tumor, Node and Metastases classification, and the Union for International Cancer Control staging, showed no positive relationship with K-ras gene mutations. No significant correlation was observed between the presence of K-ras mutations (codons 12, 13, and 61) and the survival of the patients. BRAF mutations were rare, and only two patients (1.7%) harbored a detectable mutation at codon 600.

Conclusion: K-ras gene mutation is a common event in our 118 Chinese CRC patients, with an obvious relationship with gender. However, it seems not to be an independent prognostic factor in CRC patients. The BRAF gene is rarely mutated in Chinese CRC patients.