Do evolutionary life-history trade-offs influence prostate cancer risk? a review of population variation in testosterone levels and prostate cancer disparities

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.

Keywords: challenge hypothesis; cross-cultural variation; male reproductive physiology; prostate cancer; testosterone.

Figure 1

Age-standardized incident rates of prostate cancer. Data collected from Cancer Incidence in Five Continents, Vol. IX (Curado et al. 2007).

Figure 2

Mean testosterone levels across the lifespan of men from the USA and three preindustrial societies (Ellison et al. 2002).

Figure 3

Daily per capita supply of calories, which represents the available calorie supply averaged across the population (United Nations Development Programme 2000).

Figure 4

Testosterone levels according to ethnicity and education in a sample of male American veterans; median age of the sample was 37 years (redrawn from Mazur 1995).