Intra-tumour heterogeneity

Tumour heterogeneity, per Wikipedia, is the observation that tumour cells show distinct morphological and phenotypic profiles (gene expression, metabolism, proliferation, metastatic potential) both between tumours and within a single tumour. Within-tumour heterogeneity is why one section can carry several molecular subtypes and a spread of predicted risk, and why single-sample predictions carry an irreducible uncertainty.