Abstract: Objective · To study the correlation between KRAS, NRAS and BRAF mutations and the clinicopathological features in patients with colorectal cancer (CRC). Methods · The 461 paraffin-embedded CRC tissues were collected. The mutations in hotspot region of KRAS, NRAS and BRAF genes were investigated using amplification refractory mutation system. The relationship between the mutation rates of each gene and the clinicopathological characteristics in CRC patients were analyzed. The KRAS and BRAF mutation profile and the impact on promoter methylation of the downstream genes were further investigated in both CRC tissues and cell lines through literatures and the American Type Culture Collection. Results · KRAS, NRAS and BRAF mutation rates in CRC tissues were 44.0%, 6.1% and 5.2%, respectively. KRAS mutations in the right colon were remarkably higher than the left colon (P=0.000). NRAS mutations were more likely to occur in male patients than female patients (P=0.002). BRAF mutation was closely correlated with age, tumor differentiation, tumor location and nerve invasion, but was exclusive of 203 KRAS mutated samples. Conclusion · KRAS, NRAS and BRAF mutations were significantly correlated with the clinicopathological features of CRC, and the mutation incompatibility was observed between KRAS and BRAF genes.

Key words: colorectal cancer, KRAS, NRAS, BRAF, gene mutation, clinicopathological feature