Effect of BRAF mutation on the prognosis for patients with colorectal cancer undergoing cytoreductive surgery for synchronous peritoneal metastasis

Background:KRAS/BRAF mutations(mutKRAS/mutBRAF)are unfavorable prognostic factors for colorectal cancer(CRC)metastases to the liver and lungs.However,their effects on the prognosis for patients with synchronous peritoneal metastasis(S-PM)of CRC after cytoreductive surgery(CRS)and hyperthermic intraperitoneal chemotherapy(HIPEC)are controversial.In the study,we aimed to determine the effects of mutKRAS/mutBRAF on the prognosis for patients with S-PM who received CRS.Methods:A total of 142 patients diagnosed with S-PM between July 2007 and July 2019 were included in this study.The demographics,mutKRAS/mutBRAF status,overall survival(OS),and progression-free survival(PFS)of the patients were evaluated.The Kaplan–Meier method and log-rank test were used to estimate the difference in survival between groups.Results:Among 142 patients,68(47.9%)showed mutKRAS and 42(29.5%)showed mutBRAF.The median OS values were 8.4 and 34.3 months for patients with mutBRAF and BRAF wild-type,respectively(P<0.01).However,KRAS status was not significantly associated with median OS(P=0.76).Multivariate analysis revealed carcinoembryonic antigen,CRS,HIPEC,and mutBRAF as independent predictors for OS.Based on these findings,a nomogram was constructed.The C-index was 0.789(95%confidence interval,0.742–0.836),indicating good predictive ability of the model.Furthermore,the 1-and 2-year survival calibration plots showed good agreement between the predicted and actual OS rates.The area under curves of the 1-and 2-year survival predictions based on the nomogram were 0.807 and 0.682,respectively.Additionally,mutBRAF was significantly associated with lower PFS(P<0.001).Conclusions:mutBRAF is an independent prognostic risk factor for S-PM.The established nomogram predicted the OS of patients with CRC having S-PM with high accuracy,indicating its usefulness as a valuable prognostic tool for the designated patient cohort.