Oestrogens and prostate cancer

International Congress on Hormonal Steroids and Hormones and Cancer
G P Risbridger, J J Bianco, S J Ellem and S J McPherson
Monash Institute of Reproduction and Development (Centre for Urological Research), Monash University,
Melbourne, Victoria, Australia

Men and women synthesise both androgens and oestrogens, but the relative ratio of the two hormones between the two sexes is markedly different. The importance of androgens to the male is unequivocal whereas the roles of oestrogens are less clear. Oestrogen synthesis occurs via aromatisation of androgens utilising the aromatase enzyme (cytochrome P450arom); therefore the aromatase enzyme is a critical regulator of the balance between the androgens and oestrogensthat contributes to circulating and tissue levels of these hormones. In men, the balance between systemic levels of androgens and oestrogens is altered significantly upon aging; plasma androgen levels decline whereas oestradiol levels remain relatively constant (Vermeulen et al. 2002). In specific tissues of the body, the balance between androgens and oestrogens may differ significantly from that in theplasma but is nevertheless dependent upon the presence and activity of locally produced steroid metabolising enzymes, such as 5á-reductase and aromatase (Voigt & Bartsch 1986,

Negri-Cesi et al. 1998, 1999, Weber et al. 1999, Steers 2001). The role of local synthesis of steroids has assumed increasing importance in some disease states, particularly in glandular tissue such as the breast, wherein abnormal levels of oestradiol promote the development and proliferation in the early stages of malignant transformation of epithelial cells (Simpson et al. 1994, Santen et al. 1997).
Download Article