Biology of sex and cancer

Division Of Cancer Epidemiology And Genetics

Investigators

Linked publications, trials & patents

Abstract

Sex differences are especially stark in cancer incidence and survival where men have at least a 2–3 times higher risk than women of developing and dying from most non-sex-specific cancers. Historically, this male predominance has been attributed to increased risk taking behaviors among men contrasted with the health seeking behaviors of women. However, a growing body of research is challenging these ideas to uncover sex differences in cancer incidence related to biology. For instance variations in immunity are driven by differences between males and females in sex-steroid hormones levels and gene expression, or the combination. The sex-steroid hormones progesterone and estrogen are thought to lower risk of some nonreproductive cancers in females, while testosterone promotes cell growth and is associated with increased risk of cancers in both sexes. Females have more robust innate and adaptive (particularly Th2) immune responses than males, which could reduce their susceptibility to cancer. Females also mount stronger immune responses to many oncogenic infections, including Epstein Barr virus, hepatitis B virus, hepatitis C virus (HCV), and human papillomavirus (HPV), which may alter their risk of infection-related cancers. Sex differences in cancer risk also arise from genetic mechanisms, such as the frequent escape of tumor suppressor genes from epigenetic X-chromosome inactivation. This research program seeks to understand the relative contributions of these intrinsic factors in the sex differences in cancer incidence of and survival from nonreproductive cancers.