Taking a single biopsy from just one part of a tumour may fail to provide a full picture of its genetic landscape, indicates the first study to analyse the full genome in different regions of the same tumour, which shows much greater variation in mutations than previously thought.

Two thirds (66-69%) of mutations identified in the study were not shared by different biopsies taken from the same tumour. This may help to explain why using single biopsies to identify biomarkers used to direct treatment with molecular targeted therapies has often proved unsuccessful in improving long term survival from cancer.

Researchers at Cancer Research UK’s London Research Institute and University College London’s Cancer Institute analysed the …