The goal of hormone therapy (also called androgen deprivation) is to lower the levels of the male hormones (androgens), such as testosterone, or to stop them from affecting prostate cancer cells.
In men, the main source of androgens is the testicles. The adrenal glands also make a small amount of androgens.
Androgens cause prostate cancer cells to grow. Lowering androgen levels or stopping them from getting into prostate cancer cells often makes prostate cancer shrink or grow more slowly for a time. Hormone therapy alone can control the cancer and help with symptoms, but hormone therapy alone does not cure prostate cancer.
Hormone therapy is often used:
- In men who can’t have surgery or radiation for some reason or who can’t be cured by these treatments because the cancer has already spread too far.
- For men whose cancer remains or has come back after earlier treatment with surgery or radiation.
- Along with radiation as the first treatment in men who are at high risk of having the cancer return after treatment.
- Before radiation to try to shrink the cancer and make treatment more effective.
Several types of hormone therapy can be used to treat prostate cancer. Some lower the levels of testosterone or other androgens (male hormones). Others block the action of those hormones.
Hormone therapy that lowers androgen levels
Orchiectomy: Even though this is a type of surgery, its main effect is as a form of hormone therapy. In this operation, the surgeon removes the testicles, where most of the androgens are made. This is a fairly simple operation and it is not as costly as some other options, but it is permanent and many men have trouble accepting this operation.
LHRH analogs: These drugs lower testosterone levels just as well as orchiectomy. LHRH analogs (also called LHRH agonists or GnRH agonists) are given as shots or as small pellets of medicine put under the skin. Depending on the drug used, they are given anywhere from once a month to once a year. Although the testicles stay in place, they will shrink over time. They may even become too small to feel.
When LHRH analogs are the first given, the testosterone level goes up briefly before going down to low levels. This is called flare. Men whose cancer has spread to the bones may have bone pain during this flare. To reduce flare, drugs called anti-androgens can be given for a few weeks before starting treatment with LHRH analogs.
LHRH antagonists: LHRH antagonists work like LHRH analogs, but they reduce testosterone levels more quickly and do not cause tumor flare like the LHRH analogs do. Degarelix (Firmagon®) is an LHRH antagonist used to treat advanced prostate cancer. It is given as a monthly shot under the skin.
Abiraterone (Zytiga®): Even when the testicles aren’t making androgens, other cells in the body can still make small amounts of male hormones. Abiraterone helps block these cells from making certain hormones, including androgens.
This drug is taken as pills each day. Since this drug doesn’t stop the testicles from making testosterone, men who haven’t had their testicles removed need to stay on LHRH agonist (or antagonist) treatment. Abiraterone also lowers the level of certain other hormones in the body, so prednisone (a cortisone-like drug) needs to be taken during treatment.
Drugs that stop androgens from working
Anti-androgens: Androgens have to bind to a certain protein in the prostate cancer cell to work. Most anti-androgens block androgens in the body from binding to that protein. This stops the androgens from working.
In the US, these drugs aren’t often used alone. They are sometimes used along with orchiectomy or LHRH analogs.
Enzalutamide (Xtandi®): This is a newer type of anti-androgen. It doesn’t block androgens from binding to the protein in the cell. Instead it stops the protein from sending a signal telling the cell to grow and divide. This can often help shrink tumors and help men with advanced prostate cancer live longer, even if other hormone treatments no longer work.
All of these drugs are pills and are taken daily.
Common side effects of hormone therapy
Orchiectomy, LHRH analogs, and LHRH antagonists can all cause side effects because of changes in the levels of hormones. These side effects can include:
- Less sexual desire
- Erection problems
- Hot flashes (which may get better or even go away with time)
- Breast tenderness and growth of breast tissue
- Shrinking of testicles
- Shrinking of penis
- Bone thinning (osteoporosis), which can lead to broken bones
- Low red blood cell counts (anemia)
- Decreased mental sharpness
- Loss of muscle mass
- Weight gain
- Extreme tiredness (fatigue)
- Increased cholesterol
Some research has suggested that the risk of high blood pressure, diabetes, strokes, and heart attacks, and even death from heart disease is also higher in men treated with hormone therapy. But not all studies have found this.
Many side effects can be prevented or treated. If you are thinking about hormone therapy, ask your doctor to explain what side effects you might expect to have and what can be done to manage these problems.
For more information about hormone therapy for prostate cancer, see Prostate Cancer.
Last Revised: 02/09/2016