Attribution of Cancer Origins to Endogenous, Exogenous, and Actionable Mutational Processes

Abstract

Mutational processes in tumors leave tell-tale genomic signatures composed of "passenger" mutations and mutations that have quantifiable effects on the proliferation and survival of cancer cell lineages. We identify the contributions of mutational processes to each oncogenic variant, quantifying responsibility for origination of changes at oncogenic variant sites contributing to tumorigenesis in 23 cancer types. We demonstrate that the variants driving melanomas and lung cancers are predominantly attributable to the actionable, preventable, exogenous mutational processes of ultraviolet light and tobacco exposure, whereas gliomas and prostate adenocarcinomas are largely attributable to endogenous processes associated with aging. Preventable mutations associated with pathogen exposure and APOBEC activity account for a large proportion of the cancer effect within head and neck, bladder, cervical, and breast cancers. These attributions complement epidemiological approaches--revealing the burden of cancer driven by single-nucleotide variants caused by either endogenous or exogenous, non-actionable or actionable processes, and crucially inform cancer prevention.