Evolution, Infection, and Cancer

Abstract

A balanced approach to the causes of cancer requires assessment of genetic, environmental, and infectious influences and the interactions among them. An evolutionary perspective provides a framework for such assessments because evolutionary selection acts on cells during the process of oncogenesis, on individuals to generate protection against oncogenesis, and on pathogens in ways that compromise mechanisms of protection. By distinguishing barriers to oncogenesis from restraints, essential causes can be distinguished from exacerbating causes, and the relative importance of interfering with genetic, environmental, and infectious causes can be assessed. The relevance of this framework is illustrated by evidence derived from populations in Utah that differ in their exposure to risk factors, particularly sexually transmitted pathogens and tobacco smoke. These considerations and assessment of the evidence for infectious causation of cancers lead to the conclusion that greater effort needs to be made to identify and prevent infectious causes of cancer, particularly infectious agents transmitted in sexual partnerships and by contaminated needles.