Abstract
An accumulation of evidence suggests that increased exposure to androgens is associated with prostate cancer risk. The unrestricted energy budget that is typical of Western diets represents a novel departure from the conditions in which men's steroid physiology evolved and is capable of supporting distinctly elevated testosterone levels. Although nutritional constraints likely underlie divergent patterns of testosterone secretion between Westernized and non-Western men, considerable variability exists in men's testosterone levels and prostate cancer rates within Westernized populations. Here, I use evolutionary life history theory as a framework to examine prostate cancer risk. Life history theory posits trade-offs between investment in early reproduction and long-term survival. One corollary of life history theory is the ‘challenge hypothesis’, which predicts that males augment testosterone levels in response to intrasexual competition occurring within reproductive contexts. Understanding men's evolved steroid physiology may contribute toward understanding susceptibility to prostate cancer. Among well-nourished populations of Westerners, men's testosterone levels already represent an outlier of cross-cultural variation. I hypothesize that Westernized men in aggressive social environments, characterized by intense male–male competition, will further augment testosterone production aggravating prostate cancer risk.
Highlights
Prostate cancer represents a serious and rapidly growing health concern, and is the second most common cancer among men
Modern Westernized environments represent a clear deviation from the environment in which male reproductive physiology evolved
By incorporating a challenge hypothesis framework, another source of lifetime variation in testosterone exposure was proposed: Aggressive social environments affect prostate cancer incidence through the responsiveness of male androgen physiology to challenges, among Westerners who are able to support the energetic costs of high testosterone levels
Summary
Prostate cancer represents a serious and rapidly growing health concern, and is the second most common cancer among men. Numerous risk factors for prostate cancer have been identified, including ancestry, diet, socioeconomic status (SES), and endogenous steroid concentrations (Gro€nberg 2003; Hsing and Chokkalingam 2006; Sanderson et al 2006). These factors are frequently inconsistent, showing positive associations with prostate cancer in some studies and no, or even negative, associations in others (Meikle and Stanish 1982; Kolonel 2001; Sanderson et al 2006; Roddam et al 2008; Alvarado 2010). It is my contention that commonly recognized risk factors, such as ancestry, dietary composition, and SES, will lead to higher prostate cancer rates only to the extent that they covary with socioecological factors influencing men’s testosterone levels. While other contributions to this Special Issue on Evolution and Cancer pertain to somatic evolution of neoplasia, this review addresses environmental and social conditions that affect cancer risk
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