Hormone therapy (also called androgen deprivation therapy or ADT) is part of the standard of care for advanced metastatic prostate cancer. Testosterone fuels the growth of prostate cancer, so blocking or diminishing the production of testosterone can slow the growth of the cancerous cells. There are several different types of hormone therapy for prostate cancer:
Orchiectomy: About 90% of testosterone is produced by the testicles. So orchiectomy—the surgical removal of the testicles—is an effective way to drastically reduce testosterone release. This approach has been used successfully since the 1940s. Because it’s permanent and irreversible, most men opt for drug therapy instead. The procedure is typically done on an outpatient basis in the urologist’s office. Since recovery tends to be quick and no further hormone therapy is needed, it may be an attractive choice for someone who prefers a low-cost, one-time procedure. It also may have a lower risk of cardiovascular complications and fractures compared with drug-based hormone therapy.
LHRH Agonist: LHRH, or luteinizing-hormone releasing hormone, is a hormone released by the body that initiates the production of testosterone (GnRH, or gonadotropin-releasing hormone). Blocking the release of LHRH through the use of agonists (substances that initiate a response) is one of the most common hormone therapies used in men with prostate cancer. Drugs in this class, including leuprolide (Eligard®, Lupron Depot®, and Viadur®), goserelin (Zoladex®), and triptorelin (Trelstar®), are given as regular shots: once a month, once every 3, 4, or 6 months, or once per year, depending on the drug and prescribed dosage. LHRH agonists cause a “testosterone flare” reaction, which is an initial transient rise in testosterone that happens over the first week or two after first treatment. This can result in a variety of symptoms, ranging from bone pain to urinary frequency or difficulty. Fortunately, this can be prevented by prescribing an anti-androgen, a drug that blocks the testosterone’s effects.
LHRH Antagonists: These are a newer class of medications that can block LHRH (GnRH) from stimulating testosterone production without causing an initial testosterone surge. This class includes degarelix (Firmagon®), which is taken once per month as an alternative to orchiectomy or LHRH agonists.
Anti-Androgens: Anti-androgens such as bicalutamide (Casodex®), flutamide (Eulexin®), and nilutamide (Nilandron®) can help block the action of testosterone in prostate cancer cells. They are often added to some hormone injections to prevent a temporary rise in testosterone.
Although the sexual side effects of the anti-androgens when given alone are typically fewer compared with hormone injections, anti-androgens might not be as effective as orchiectomy or hormone injections, and they are not the optimal choice for men with documented metastatic prostate cancer. Furthermore, when given alone, >70% of men experience breast tenderness or the formation/growth of breast tissue, called gynecomastia.
When used in combination with LHRH agonists, anti-androgens tend to increase the risk of hot flashes, and in rare occasions can result in liver injury. Your liver function should be monitored while you take these medications. Fortunately, gynecomastia is rare when LHRH agonists and anti-androgens are used together.
In addition, nilutamide is known to cause visual light-dark adaptation problems and—rarely—cause inflammation and scarring in the lungs. If you develop a persistent cough or persistent shortness of breath while on nilutamide, you should contact your doctor.