Abstract

Mutational signatures are the imprints of the biological processes that have gone awry in human cells. We previously outlined the methods for identifying and quantifying base substitution mutational signatures present in primary human cancers (http://cancer.sanger.ac.uk/cosmic/signatures). Here, using a highly-curated cohort of 560 whole genome sequenced breast cancers, we extend the understanding of mutational signatures to include six novel rearrangement signatures. We further demonstrate how mutational signatures can report on subclonal architecture of the cancer genome distinguishing clinically relevant subpopulations in breast cancer.