Correlation of RAS mutations and microsatellite instability with clinico-pathological features and prognosis of patients with stage Ⅲ colorectal cancer / 中国病理生理杂志

ABSTRACT

AIM:To investigate the status of RAS/BRAF mutations and microsatellite instability ( MSI ) and their associations with clinicopathological features and prognosis of the patients with stage Ⅲ colorectal cancer ( CRC ) . METHODS:The surgical patients with stage ⅢCRC (n=281) were followed up.The mutations of RAS/BRAF were ex-amined by PCR amplification-Sanger sequencing , and MSI status was detected using immunohistochemistry ( IHC) in their archival paraffin-embedded tissue specimens .The relationships of the status with the clinicopathological features and prog-nosis of the patients were statistically analyzed .RESULTS: Among 281 patients, the mutations of RAS/BRAF were ob-served in 136 cases (48.4%), including 116 cases (41.3%) of KRAS mutations.RAS/BRAF mutations were highly cor-related with the level of carcino-embryonic antigen (P<0.05).Moreover, 18 cases (6.4%) of MSI-high (MSI-H) pa-tients were determined by IHC, and MSI-H status was more common in N2b patients (P<0.05).Correlation study found that the mutation rate of BRAF was higher in MSI-H tumors than that in MSI-low ( MSI-L)/microsatellite stability ( MSS) counterparts (P<0.01), although no association between KRAS/NRAS mutations and the MSI status was observed .The prognosis in the patients with wild-type RAS/BRAF or MSI-H was better than the patients with any mutation or MSI-L/MSS (P<0.01).CONCLUSION:Mutant RAS/BRAF and MSI may serve as fairly good indicators for prognosis of the patients with stage Ⅲ CRC.