KRAS and colorectal cancer: Two databases (MEDLINE and Embase) were searched using the following search strategy: “colorectal cancer” or “colorectal neoplasms”, “tumour stage”, “nodal stage”, “metastasis” or “distant metastasis”, “tumour size”, “BRAF” or “BRAF mutation”, “KRAS” or “KRAS mutation”, “tumour budding”, “tumour location”, “tumour infiltrating lymphocytes”, “CDX2 mutation”, “lymph node yield”, “lymph node ratio”, “apical lymph node status”, “perineural invasion”, “circumferential resection margin”, “tumour grade”, “lymphovascular invasion” and “prognosis”.