Mlecnik et al. analysed the genetics, levels of genomic instability, vascularization and the immunoscore (a measure of the 'immune contexture' of the tumour microenvironment) in a cohort of colorectal cancers. They found that FBXW7 mutations were inversely correlated with metastasis; genomic instability did not correlate with metastasis. However, decreased lymphatic vascularity and reduced immune cytotoxicity were strongly associated with metastasis, suggesting that the tumour microenvironment has a dominant role in metastasis.