Phytoestrogens selective for the estrogen receptor beta exert anti-androgenic effects in castration resistant prostate cancer

• We review novel targeted therapies for castration resistant prostate cancer (CRPC).
• The pivotal therapy target in CRPC is the androgen receptor.
• The estrogen receptor-β is a tumour suppressor in prostate cancer.
• The estrogen receptor-β has anti-androgenic characteristics.
• Estrogen receptor sub-type selective ligands have therapeutic potential in CRPC.

Prostate cancer is the leading cause of cancer death in men of the Western world. A castration-resistant prostate cancer (CRPC) eventually will arise when a local restricted prostate carcinoma was not cured duly by radical prostatectomy or radiation therapy. Although androgen ablation therapies are considered the gold standard for treatments of advanced prostate cancer there is no curative therapy available at present. In previous pre-clinical and clinical trials several phytoestrogens were investigated for their anticancer potential in various models for prostate cancer. Phytoestrogens feature tumour preventive characteristics and most probably are involved in the low incidence rate of hormone related cancers in Asian countries. Phytoestrogens such as isoflavones can have a marked impact on the most essential therapy target of CRPC i.e. the androgen receptor. Furthermore, functional analyses solidified the notion of such drugs as androgen antagonistic. Phytoestrogens commonly feature low toxicity combined with a potential of targeted therapy. Thus, these drugs qualify for conceivable implementation in prostate cancer patients under active surveillance. In addition, relapse prevention with these drugs after radical prostatectomy or radiation therapy might be considered.This article is part of a Special Issue entitled ‘Phytoestrogens’.