When you have prostate cancer, male sex hormones (androgens) can stimulate the growth of cancer cells. The main type of androgen is testosterone. Hormone therapy either uses drugs to try to stop your body from producing male sex hormones, or involves surgery to remove your testicles, which produce most of your testosterone. This type of therapy can also block hormones from getting into cancer cells. Sometimes doctors use a combination of drugs to achieve both.
In most men with advanced prostate cancer, this form of treatment is effective in helping to slow the growth of tumors. Because it's effective at shrinking tumors, doctors use hormone therapy in some early-stage cancers — often in combination with radiation and sometimes with surgery. Hormones shrink large tumors so that surgery or radiation can remove or destroy them more easily. After these treatments, the drugs can inhibit the growth of stray cells left behind.
Some drugs used in hormone therapy decrease your body's production of testosterone. The hormones — known as luteinizing hormone-releasing hormone (LH-RH) agonists — can set up a chemical blockade. This blockade prevents the testicles from receiving messages to make testosterone. Drugs typically used in this type of hormone therapy include leuprolide (Lupron, Viadur) and goserelin (Zoladex). They're injected into a muscle or under your skin once every three or four months. You can receive them for a few months, a few years, or the rest of your life, depending on your situation.
Other drugs used in hormone therapy block your body's ability to use testosterone. A small amount of testosterone comes from the adrenal glands and won't be suppressed by leuprolide or goserelin. Certain medications — known as anti-androgens — can prevent testosterone from reaching your cancer cells. Drugs typically used for this type of therapy include flutamide (Eulexin), bicalutamide (Casodex) and nilutamide (Nilandron). They come in tablet form and, depending on the particular brand of drug, are taken orally one to three times a day. These drugs typically are given with an LH-RH agonist.
Simply depriving prostate cancer of testosterone usually doesn't kill all of the cancer cells. Within a few years, the cancer often learns to thrive without testosterone. Once this happens, hormone therapy is less likely to be effective. However, several treatment options still exist.
To avoid such resistance, intermittent hormone therapy programs have been developed. During this type of therapy, the hormonal drugs are stopped after your PSA drops to a low level and remains steady. You resume taking the drugs if your PSA level rises again.
Side effects of hormone therapy may include breast enlargement, reduced sex drive, impotence, hot flashes, weight gain and reduction in muscle and bone mass. Some of these drugs can also cause nausea, diarrhea, fatigue and liver damage.
Because most testosterone is produced in your testicles, surgical removal of your testicles (castration) also can be an effective form of therapy — especially for advanced prostate cancer. The procedure can be performed on an outpatient basis using a local anesthetic.