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.
