Tumour evolution inferred by single-cell sequencing

Single tumour cells observed Tumours are known to be genetically heterogeneous, but it is proving difficult to dissect this heterogeneity at the single-cell level. A combination of whole-genome amplification and sequencing of single nuclei separated by fluorescence activated cell sorting now reveals the population structure of breast tumours from two patients. In both, tumour growth is by punctuated clonal expansions with few persistent intermediates, in contrast to the many gradual models of tumour progression. Single-cell sequencing of this type — once it becomes cheaper — is likely to have clinical implications for cancer prognosis and staging.