Hormone Therapy
Hormone therapy starves the cancer cells of testosterone by using drugs that inhibit testosterone production.
Prostate cancer is initially dependent on male hormones, or androgens, for growth. The primary androgen is testosterone. Hormone therapy, or androgen suppression therapy, is used for patients whose prostate cancer has spread outside the prostate or has recurred after initial treatment.
By blocking androgens, hormone therapy causes prostate cancer to shrink, or to grow more slowly. It does not ‘cure’ the cancer, but can keep it at bay or ‘in remission’ for several years.
Hormone therapy blocks androgens from fueling the growth of prostate cancer by blocking the production of testosterone or either the cancer cell’s ability to use it.
How Hormone Therapy Works
Luteinizing hormone-releasing hormone (LH-RH) agonists stop the pituitary from instructing the testes to produce testosterone. LH-RH drugs make the pituitary release all of its Luteinizing Hormone (LH), which causes a “flare” of increased testosterone. This causes the pituitary to stop producing LH, which then stops the testes from producing testosterone. LH-RH agonist drugs are administered by injection every three or four months.
Anti-androgens block the body’s ability to use all androgens, including those made by the adrenal glands, and can be used with LH-RH agonists to set up a total androgen blockade. They usually come in tablet form.
Most prostate cancers treated with hormone therapy eventually become androgen-independent (AIPC), or hormone-refractory (HRPC). They learn to live without androgens and begin to grow again after a median period of 16 to 24 months, though some take longer and others will take a shorter amount of time. These cancers need to be treated by other methods, some of which are available through participating in clinical trials that test experimental drugs and treatments.
Intermittent hormone therapy, or stopping hormone therapy whenever the PSA level returns to a stable, low level, is sometimes used in an attempt to prevent cells from developing resistance to treatment.
Other drugs, such as estrogen or ketoconazole, can be used and may be effective after other drugs have stopped working.
Sometimes hormone therapy is combined with surgery or radiation, either to shrink tumors in advance of treatment or to inhibit the growth of cancer cells in men with a high risk of prostate cancer recurrence.
As most testosterone is produced in the testicles, surgical removal of the testes, or orchiectomy, is also an effective way to block hormone production. However, many men prefer to use hormone blockade drugs, even though they can be more expensive, as they can work just as well as surgery and the effects are reversible.
