Mutation patterns in cancer genomes

Abstract

Recent large-scale cancer sequencing studies have focused primarily on identifying cancer-associated genes, but as an important byproduct provide "passenger mutation" data that can potentially illuminate the mutational mechanisms at work in cancer cells. Here, we explore patterns of nucleotide substitution in several cancer types using published data. We first show that selection (negative or positive) has affected only a small fraction of mutations, allowing us to attribute observed trends to underlying mutational processes rather than selection. We then show that the increased CpG mutation frequency observed in some cancers primarily occurs outside of CpG islands and CpG island shores, thu..