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. Four LHRH agonists are approved to treat prostate cancer in the United States: leuprolide (Lupron), goserelin (Zoladex), triptorelin (Trelstar), and histrelin (Vantas). LHRH agonists are given by injection or are implanted under the skin. Once treatment is stopped, androgen production usually resumes. But, unlike surgical castration (orchiectomy), the effects of these drugs on androgen production are reversible. Treatment with an LHRH agonist is called medical castration or chemical castration. However, the continued presence of high levels of LHRH agonists actually causes the pituitary gland to stop producing luteinizing hormone. As a result, the testicles are not stimulated to produce androgens. LHRH agonists, like the body’s own LHRH, initially stimulate the production of luteinizing hormone.
This stimulates the pituitary gland to produce luteinizing hormone, which in turn stimulates the testicles to produce androgens. Normally, when androgen levels in the body are low, the hypothalamus releases LHRH. (LHRH is also known as gonadotropin-releasing hormone or GnRH, so LHRH agonists are also called GnRH agonists or GnRH analogs.) 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. Drugs called luteinizing hormone-releasing hormone (LHRH) agonists, which prevent the pituitary gland from secreting a hormone called luteinizing hormone.Orchiectomy 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. Removal of the testicles, called surgical castration, can reduce the level of testosterone in the blood by 90% to 95% ( 5). Orchiectomy, a surgical procedure to remove one or both testicles.
This form of hormone therapy (also called androgen deprivation therapy, or ADT) includes: Treatments that reduce androgen production by the testicles are the most commonly used hormone therapies for prostate cancer and the first type of hormone therapy that most men with prostate cancer receive. Androgens are taken up by prostate cells, where they either bind to the androgen receptor directly or are converted to dihydrotestosterone (DHT), which has a greater binding affinity for the androgen receptor than testosterone. Most of the remaining androgens are produced by the adrenal glands.
LH acts on specific cells in the testes to produce the majority of testosterone in the body. The hypothalamus releases LHRH, which stimulates the release of LH from the pituitary gland. Drawing shows that testosterone production is regulated by luteinizing hormone (LH) and luteinizing hormone-releasing hormone (LHRH). How does hormone therapy work against prostate cancer?Īndrogen production in men. Although prostate cells do not normally make testosterone, some prostate cancer cells acquire the ability to do so ( 3). Once activated, the androgen receptor stimulates the expression of specific genes that cause prostate cells to grow ( 2).Īlmost all testosterone is produced in the testicles a small amount is produced by the adrenal glands. Androgens promote the growth of both normal and cancerous prostate cells by binding to and activating the androgen receptor, a protein that is expressed in prostate cells ( 1). Androgens are also necessary for prostate cancers to grow. The most abundant androgens in men are testosterone and dihydrotestosterone (DHT).Īndrogens are required for normal growth and function of the prostate, a gland in the male reproductive system that helps make semen. Hormones circulate in the bloodstream and control the actions of certain cells or organs.Īndrogens (male sex hormones) are a class of hormones that control the development and maintenance of male characteristics. Hormones are substances that are made by glands in the body.