What types of hormone therapy are used for prostate cancer?

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Hormone therapy for prostate cancer—also called androgen suppression therapy or androgen deprivation therapy—can block the production and use of androgens.3 Currently available treatments can:

  • Reduce androgen production by the testicles
  • Block the action of androgens in the body
  • Block the production of androgens throughout the body

Treatments that reduce androgen production by the testicles are the most commonly used hormone therapies for prostate cancer. These include:

• Orchiectomy, a surgical procedure to remove one or both testicles. Removal of the testicles can reduce the level of testosterone in the blood by 90 to 95 percent.4 This type of treatment, called surgical castration, is permanent and irreversible. A type of orchiectomy called subcapsular orchiectomy removes only the tissue in the testicles that produces androgens, rather than the entire testicle.

• Drugs called luteinizing hormone-releasing hormone (LHRH) agonists, which prevent the secretion of a hormone called luteinizing hormone. LHRH agonists, which are sometimes called LHRH analogs, are synthetic proteins that are structurally similar to LHRH and bind to the LHRH receptor in the pituitary gland. (LHRH is also known as gonadotropin-releasing hormone or GnRH, so LHRH agonists are also called GnRH agonists.)

Normally, when androgen levels in the body are low, LHRH stimulates the pituitary gland to produce luteinizing hormone, which in turn stimulates the production of androgens by the testicles. LHRH agonists, like the body’s own LHRH, initially stimulate the production of luteinizing hormone. However, the continued presence of high levels of LHRH agonists actually causes the pituitary gland to stop producing luteinizing hormone, which prevents testosterone from being produced. Treatment with an LHRH agonist is called medical castration (sometimes called chemical castration) because it uses drugs to lower androgen levels in the body to the same extent as surgical castration (orchiectomy). But, unlike orchiectomy, the effects of these drugs on androgen production are reversible. Once treatment is stopped, androgen production usually resumes.

LHRH agonists are given by injection or are implanted under the skin. Two LHRH agonists, leuprolide and goserelin, are approved to treat prostate cancer in the United States.

When patients receive an LHRH agonist for the first time, they may experience a phenomenon called “testosterone flare.” This temporary increase in testosterone level occurs because LHRH agonists briefly cause the pituitary gland to secrete extra luteinizing hormone before blocking its release. The flare may worsen clinical symptoms (for example, bone pain, ureter or bladder outlet obstruction, and spinal cord compression), which can be a particular problem in men with advanced prostate cancer. The increase in testosterone is usually countered by giving another type of hormone therapy called antiandrogen therapy (described below) along with an LHRH agonist for the first few weeks of treatment.

• Drugs called LHRH antagonists, which are another form of medical castration. LHRH antagonists (also called GnRH antagonists) act by preventing LHRH from binding to its receptors in the pituitary gland, which in turn prevents the secretion of luteinizing hormone, causing the body’s androgen levels to drop. Unlike LHRH agonists, LHRH antagonists do not cause a testosterone flare. One LHRH antagonist, degarelix, is currently approved to treat advanced prostate cancer in the United States. It is given by injection.

• Estrogens (hormones that promote female sex characteristics). Although estrogens are also able to inhibit androgen production by the testicles, they are seldom used today in the treatment of prostate cancer because of their side effects.