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 60years (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.