Hormone therapy is used to lessen or eliminate the supply of male hormones in the body in an effort to stop or slow the growth of prostate cancer cells. Male hormones, also called androgens, stimulate prostate cancer cells to grow. The main androgens are testosterone and dihydrotestosterone (DHT) and they are produced primarily in the testicles.
Hormone therapy is also called androgen deprivation therapy (ADT) and androgen suppression therapy. Hormone therapy does not cure prostate cancer but it can cause it to grow more slowly.
A man with prostate cancer may have hormone therapy before, during or after radiation therapy. Hormone therapy is also used alone for prostate cancer that has returned after treatment.
Hormone therapy is usually used in the following situations:
• To shrink or slow the growth of cancer that has spread beyond the prostate gland
• After surgery or radiation to shrink or slow the growth of any cancer cells that remain
• In addition to radiation if a patient is at high risk for recurrence
• In men with early stage prostate cancer before surgery or radiation to try to shrink the cancer to make other treatments more effective
Side effects can include:
- Reduced or absent libido (sexual desire)
- Hot flashes
- Breast tenderness and growth of breast tissue
- Osteoporosis (bone thinning), which can lead to broken bones
- Anemia (low red blood cell counts)
- Decreased mental acuity
- Loss of muscle mass
- Weight gain
- Increased cholesterol
- Increased risk of hypertension (high blood pressure), diabetes, and heart attacks
Types of hormone therapy
Surgery to remove the testicles
This procedure is called orchiectomy and lowers the amount of male hormones in the body by removing the testicles where androgens, mostly testosterone, are produced. The effectiveness of orchiectomy in lowering testosterone levels is similar to that of hormone therapy medications, but orchiectomy may lower testosterone levels more quickly. With this source removed, most prostate cancers stop growing or shrink for a time.
Orchiectomy is done as a simple outpatient procedure and is the easiest way to reduce androgen levels in the body. However, unlike some of the other methods of lowering androgen levels, it is permanent, and for many men there are psychological and emotional side effects of this procedure.
Medications that stop the production of hormones
Known as luteinizing hormone-releasing hormone (LH-RH) agonists, these drugs prevent the testicles from receiving messages to make testosterone.
Medications that lower the production of androgens
Called luteinizing hormone-releasing hormone (LHRH) analogs, these drugs lower the amount of testosterone produced by the testicles. LHRH analogs are injected or placed as small implants under the skin and are given anywhere from once a month up to once a year. This treatment is often chosen over orchiectomy because it reduces androgen levels as well as orchiectomy but it allows the testicles to remain in place. With this procedure, a patient’s testicles will shrink over time and may eventually become too small to feel.
Medications that block testosterone from reaching cancer cells
Medications known as anti-androgens prevent testosterone from reaching cancer cells. These drugs typically are given along with an LH-RH agonist or given before taking an LH-RH agonist. Anti-androgens block the body's ability to use any androgens. Even after orchiectomy or during treatment with LHRH analogs, a small amount of androgens is still made by the adrenal glands.
Anti-androgens are not often used by themselves and may be added if treatment with orchiectomy or an LHRH analog is no longer working by itself. An antiandrogen is sometimes given for a few weeks when an LHRH analog is first started to prevent a tumor flare.