Clinical meaning of BRAF mutation in Korean patients with advanced colorectal cancer

AIM:To evaluate the clinicopathological features ofcolorectal cancer(CRC)with a v-Raf murine sarcomaviral oncogene homolog B1(BRAF)mutation and itsmolecular interaction with microsatellite instability(MSI)and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog(KRAS)in patients with advanced CRCs.METHODS:From October 2009 to December 2011,141 patients with stageⅢ(n=51)orⅣ(n=90)CRCs who were tested for the BRAF mutation at Severance Hospital were included.Among 141 patients,fivewere excluded due to follow-up loss.Therefore,136patients were included in the study.The clinicopathological data,MSI status,and KRAS/BRAF mutation status were reviewed retrospectively.In addition,to evaluating the value of BRAF mutation status,progressionfree survival and overall survival in all patients werecollected and compared between the BRAF wild-typegroup and BRAF mutation group.RESULTS:Of 136 patients,80(58.8%)were male and the mean age was 59 years.BRAF and KRAS mutations were detected in 9.6%and 35.3%of patients,respectively.Only 4.3%of patients had MSIhigh tumors and there were no MSI-high in tumors with a BRAF mutation.BRAF mutations tended to be more frequent in stageⅣthan in stageⅢ(11.76%vs 5.88%,P=0.370).Patients with a BRAF mutation had a lower incidence of KRAS mutation than those without(7.69%vs 38.21%,P=0.033).Overall survival was significantly shorter in the BRAF mutation group than in the BRAF wild-type group both by univariate analysis(P=0.041)and multivariate analysis(HR=2.195;95%CI:1.039-4.640;P=0.039),while progression-free survival was not different according to BRAF mutation status.CONCLUSION:CRCs with a BRAF mutation have distinct molecular features and resulted in a poor prognosis in Korean patients with advanced CRC.