Hormonal therapy, also known as androgen deprivation therapy (ADT), keeps cancer cells from getting the male hormones they need to grow. It is called systemic therapy because it can affect cancer cells throughout the body. Systemic therapy is used to treat cancer that has spread. Sometimes this type of therapy is used to try to prevent the cancer from coming back after surgery or radiation treatment.

There are several forms of Androgen Deprivation Therapy:

• Orchiectomy is surgery to remove the testicles, which are the main source of male hormones. Although it is a surgical treatment, orchiectomy is considered a hormone therapy because it works by removing the main source of male hormones.
• Drugs known as luteinizing hormone-releasing hormone (LR-RH) agonists can prevent the testicles from producing testosterone. These drugs are injected or placed as small implants under the skin either monthly or every 3, 4 or 12 months. Examples are leuprolide, goserelin, and buserelin. All are about equally effective. They work by actually stimulating the pituitary gland to release hormones that cause testosterone production. After about 3 weeks, the pituitary gland "runs out" of these hormones and testosterone production drops.

This action is important to understand because early in treatment with LR-RH agonists there can be a surge of testosterone production causing a temporary growth of the tumor(s). If the cancer is in the bones, a patient may feel more bone pain. This is called a "flare" reaction. Flare can often be avoided by giving drugs called anti-androgens (described below) for a few weeks when starting treatment with LH-RH agonists.

• Even if a man no longer gets testosterone (an androgen) from his testicles, his adrenal glands still produce a small amount. Drugs known as anti-androgens can block the action of androgens. Two examples are Flutamide and bicalutamide. Drugs of this type are taken as pills, up to 3 times a day. Anti-androgens can be used alone, but are often combined with LH-RH agonists (described above). This is called combination hormone therapy, or total androgen blockade. Doctors do not know for sure whether total androgen blockade is more effective than orchiectomy or an LH-RH agonist alone.
• Other drugs that can prevent the adrenal glands from making androgens include Ketoconazole and aminoglutethimide.

Prostate cancer that has spread to other parts of the body usually can be controlled with hormonal therapy for a period of time, often several years. Eventually, however, most prostate cancers are able to grow with very little or no male hormones. When this happens, hormonal therapy is no longer effective, and the doctor may suggest other forms of treatment that are under study.

Side Effects

After orchiectomy (castration), about 90% of men have reduced or absent libido (sexual desire) and ED. Over half of men have hot flashes (sudden rushes of body heat) after surgery, but these may go away with time.

Side effects of luteinizing hormone-releasing hormone (LH–RH) agonists are the same as with an orchiectomy and include reduced or absent sexual desire, ED, and hot flashes. Some men also have breast tenderness and growth of breast tissue (called gynecomastia). Breast growth usually occurs in men who take estrogen therapy. Using LH–RH agonists over a long period of time can also cause osteoporosis (weakening of bones), fatigue, muscle wasting, and change in fat distribution. These side effects occur about as commonly as after orchiectomy.

A possible short-term side effect of LH–RH agonists is what is known as tumor flare. When first given, these medicines can cause a temporary rise in testosterone levels, which can cause pain at tumor sites, especially if the cancer has already spread to bone. To prevent this, a short course of anti-androgens (at least 7 days) may be given when the LH–RH agonist is first started.

Side effects of anti-androgens in patients already treated by orchiectomy or with LH–RH agonists are usually not serious or common, but may include nausea, diarrhea, tiredness, liver disease, and the growth of breast tissue, especially with prolonged use.