BRAF mutation is associated with distinct clinicopathological characteristics in colorectal cancer: A systematic review and meta-analysis

Aim: Colorectal cancer is a heterogeneous disease with multiple underlying genetic mutations resulting in different phenotypes. Mutation in the v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) proto-oncogene is an important event in the methylator pathway. There is no consensus, however, on the clinicopathological characteristics associated with BRAF mutation. Method: A comprehensive search for published studies examining the effect of BRAF mutation on colorectal cancer was performed. Random effects methods were used to combine data. Results: Data were retrieved from 21 studies describing 9885 patients. BRAF associated colorectal cancer is associated with proximal tumour location (OR 5.222, 95% CI 3.801-7.174, P < 0.001), T4 tumours (OR 1.761, 95% CI 1.164-2.663, P = 0.007) and poor differentiation (OR 3.816, 95% CI 2.714-5.365, P < 0.001) and is negatively associated with male sex (OR 0.623, 95% CI 0.505-0.769, P < 0.001), age of diagnosis under 60 years (OR 0.453, 95% CI 0.280-0.733, P = 0.001) and rectal cancer (OR 0.266, 95% CI 0.122-0.422, P < 0.001). Conclusion: BRAF mutation appears to be associated with distinct, unfavourable clinicopathological characteristics in colorectal cancer.