Centre for Urological Research

Hormones in cancer

Prostate Cancer
In Australia, prostate cancer (PCa) is the most commonly diagnosed type of cancer and the second most common cause of cancer deaths in men. Androgens are well known to play an important role in the prostate and in prostate cancer. Indeed, androgen ablation therapy has been the mainstay treatment for PCa for in excess of 6 decades. Despite this, PCa inevitably processes to an androgen independent state that is invariable fatal. Consequently new therapeutic options are desperately needed.

Although androgens play an important role in the development of PCa, we are now beginning to recognise that estrogens play an equally important role. As our understanding of the role of estrogen improves, targeting estrogens has emerged as a potential therapeutic option for the treatment of PCa. The actions of estrogen in the prostate, however, are complicated.

Estrogen has dual roles mediated by estrogen receptor α (ERα) and estrogen receptor β (ERβ) that are both adverse and beneficial, respectively. Although equivocal, emerging data has indicated that ERβ specifically mediates anti-proliferative and pro-apoptotic effects within the prostate. If correct, the targeted activation of ERα and ERβ regulated genes would be a valid new option for the treatment of PCa.

Breast Cancer
Approximately 70% of human breast cancers express the estrogen receptor (ER) and are said to be hormone dependent. Women who have undergone a full-term pregnancy/birth (parity) before 20 years of age have a 50% reduced lifetime risk of developing hormone responsive (ER positive) breast cancer compared to those women who have never had children. The mechanisms underlying this protection are unclear, but can be induced by estrogen treatment.