Your doctor may suggest hormone therapy if you have advanced or high-risk prostate cancer at the time of your diagnosis, if your prostate-specific antigen (PSA) level is rising despite previous treatment for prostate cancer, or if you aren’t able to have surgery or radiation therapy for your disease. Hormone therapy keeps prostate cancer cells from getting testosterone, a hormone that may cause prostate cancers to grow.
There are several ways to accomplish this.
- With drugs that prevent the production of testosterone in the body
- With drugs that block the action of testosterone that has already been produced
- With surgery to remove the testicles, the main source of testosterone in men
Benefits of Hormone Therapy for Prostate Cancer
Hormone therapy is among the most effective forms of systemic therapy (about 85 to 90 percent effective) for prostate cancer. Used alone, hormone therapy does not cure prostate cancer, but it does stop the disease from progressing for a period of time. Hormone therapy is increasingly being used before, during, or after other prostate cancer treatments to shrink the cancer, slow its growth, or decrease the risk of cancer returning.
Typically, you can expect hormone therapy to control your prostate cancer for at least one to four years and possibly for as long as 10 years or more. Eventually, however, the prostate cancer cells adjust to the lack of hormones and begin to grow again.
How Hormone Therapy Works
Androgens, which are male hormones, stimulate the growth of prostate cancer cells. The main androgen in men is testosterone. In healthy men, the testes make about 90 percent of testosterone, and the adrenal glands and other cells make the remainder. When the hypothalamus (part of the brain) detects low testosterone levels, hormones from the hypothalamus and pituitary gland trigger testosterone production. When the body detects the testosterone increase, the process stops.
Hormone therapy for prostate cancer, also called androgen-deprivation therapy or androgen-suppression therapy, reduces androgen levels in the body or prevents androgen from reaching prostate cancer cells. While most prostate cancer cells are affected by the elimination of androgen, some are unaffected and continue to grow. Prostate cancers that grow even when blood levels of testosterone are extremely low are called castration-resistant prostate cancers. Some castration-resistant cancers do respond to other hormone treatments, as discussed below.
If you’re on hormone therapy, your doctor will monitor your PSA levels with frequent blood tests to make sure the therapy is working for you.
Types of Hormone Therapy for Prostate Cancer
Several types of hormone therapy are available, including LHRH agonists, LHRH antagonists, anti-androgens, androgen-synthesis inhibitors, new-generation anti-androgens, other drugs, and surgical removal of the testicles. Read more about types of hormone therapy for prostate cancer.
Side Effects of Hormone Therapy
Any man considering hormone therapy should weigh the risks and benefits of the treatment. The side effects of hormone therapy and the time it takes to get over some of them depend on many factors. Read more about side effects of hormone therapy for prostate cancer.
Resistance to Hormone Therapy
For many years doctors believed that prostate cancer would always become resistant to hormone therapy over time. Much work by Seattle Cancer Care Alliance (SCCA) investigators has focused on trying to prevent resistance. We have shown that cancers become resistant to testosterone-lowering treatments by finding a way to convert other hormones, or even cholesterol, in the blood to make testosterone within the cancer itself.
At SCCA, we have designed clinical studies using many of the newer, more effective systemic therapies for hormone regulation, such as abiraterone (Zytiga) and enzalutamide (Xtandi), in combination with surgery or radiation earlier in the treatment of high-risk prostate cancers. Through these studies, men have access to drugs that may not otherwise be available and that may more effectively suppress or kill cancer cells, resulting in longer survival for men whose cancer grows in the absence of androgens.