Treating Prostate Cancer With Hormone Therapy

For men with advanced prostate cancer, hormone therapy is a treatment option. The goal is to reduce levels of male hormones, called androgens or testosterone, in the body, or to prevent them from reaching prostate cancer cells. Using drugs to decrease the testosterone is one of the most common methods of treating advanced prostate cancer.

The main androgens are testosterone and dihydrotestosterone (DHT). Most of the body’s androgens come from the testicles, but the adrenal glands also make a small amount. Androgens stimulate prostate cancer cells to grow. Lowering androgen levels or stopping them from getting into prostate cancer cells often makes prostate cancers shrink or grow more slowly for a time. However, hormone therapy alone does not cure prostate cancer and eventually, it stops helping.

Hormone therapy may be used:

• If you are not able to have surgery or radiation or can’t be cured by these treatments because the cancer has already spread beyond the prostate gland
• If your cancer remains or comes back after treatment with surgery or radiation therapy
• Along with radiation therapy as initial treatment if you are at higher risk of the cancer coming back after treatment (based on a high Gleason score, high PSA level, and/or growth of the cancer outside the prostate)
• Before radiation to try to shrink the cancer to make treatment more effective

Several types of hormone therapy can be used to treat prostate cancer. Some lower the levels of testosterone or other androgens (male hormones). Others block the action of those hormones.

Treatments to lower androgen levels

Orchiectomy (surgical castration)

Even though this is a type of surgery, its main effect is as a form of hormone therapy. In this operation, the surgeon removes the testicles, where most of the androgens (testosterone and DHT) are made. With this source removed, most prostate cancers stop growing or shrink for a time.

This is done as a simple outpatient procedure. It is probably the least expensive and simplest way to reduce androgen levels in the body. But unlike some of the other methods of lowering androgen levels, it is permanent, and many men have trouble accepting the removal of their testicles.

Some men having the procedure are concerned about how it will look afterward. If wanted, artificial silicone sacs can be inserted into the scrotum. These look much like testicles.

Luteinizing hormone-releasing hormone (LHRH) drugs

These drugs lower the amount of testosterone made by the testicles. Treatment with these drugs is sometimes called chemical castration because they lower androgen levels just as well as orchiectomy.

Even though LHRH analogs (also called LHRH agonists) cost more than orchiectomy and require more frequent doctor visits, most men choose this method. These drugs allow the testicles to remain in place, but the testicles will shrink over time, and they may even become too small to feel.

LHRH analogs are injected or placed as small implants under the skin. Depending on the drug used, they are given anywhere from once a month up to once a year. The LHRH analogs available in the United States include leuprolide (Lupron®, Eligard®), goserelin (Zoladex®), triptorelin (Trelstar®), and histrelin (Vantas®).

When LHRH analogs are first given, testosterone levels go up briefly before falling to very low levels. This effect is called flare and results from the complex way in which LHRH analogs work. Men whose cancer has spread to the bones may have bone pain. If the cancer has spread to the spine, even a short-term increase in tumor growth as a result of the flare could compress the spinal cord and cause pain or paralysis. Flare can be avoided by giving drugs called anti-androgens for a few weeks when starting treatment with LHRH analogs. (Anti-androgens are discussed further on.)

Degarelix (Firmagon®)

Degarelix is an LHRH antagonist. LHRH antagonists work like LHRH agonists, but they reduce testosterone levels more quickly and do not cause tumor flare like the LHRH agonists do.

This drug is used to treat advanced prostate cancer. It is given as a monthly injection under the skin and quickly reduces testosterone levels. With degarelix no anti-androgens are necessary. The most common side effects are problems at the injection site (minimal pain, redness, and swelling) and increased levels of liver enzymes on lab tests. Other side effects are discussed in detail below.

Abiraterone (Zytiga®)

Drugs such as LHRH agonists can stop the testicles from making androgens, but other cells in the body, including prostate cancer cells themselves, can still make small amounts, which may fuel cancer growth. Abiraterone blocks an enzyme called CYP17, which helps stop these cells from making certain hormones, including androgens.

Abiraterone can be used in men with advanced castrate-resistant prostate cancer (cancer that is still growing despite low testosterone levels from LHRH agonists, LHRH antagonists, or orchiectomy). Abiraterone has been shown to shrink or slow the growth of some of these tumors and help some of these men live longer.

This drug is a pill and the most common dose is 4 pills every day. Since this drug doesn’t stop the testicles from making testosterone, men who haven’t had an orchiectomy need to continue with treatment to stop the testicles from making testosterone (LHRH agonist or antagonist therapy). Because abiraterone lowers the level of other hormones in the body, prednisone (a cortisone-like drug) needs to be taken during treatment as well to avoid the side effects caused by lower levels of these other hormones.

Bottom Line:  Nearly 250,000 cases of prostate cancer are identified each year.  Nearly 40,000 men die from prostate cancer, second most common cause of death due to dancer after lung cancer.  For men who have elevated PSA levels after treatment, hormonal therapy is a consideration.