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Hormone Therapy

Cancer Treatment for Certain Hormone-Sensitive Cancers

The term "hormone therapy" might make you think of women taking estrogen to reduce their symptoms of menopause or men taking testosterone to slow the effects of aging. But hormone therapy for cancer — also called endocrine therapy — is something completely different. Hormone therapy for cancer alters the hormones in your body to help control or cure cancer.

Hormone therapies associated with menopause and aging seek to increase the amount of certain hormones in your body to compensate for age- or disease-related hormonal declines. But hormone therapy as a cancer treatment either reduces the level of specific hormones in your body or alters your cancer's ability to use these hormones to grow and spread.

If your cancer is one that is sensitive to hormones, you might benefit from hormone therapy as part of your cancer treatment. Learn the basics of hormone therapy, how it works as a cancer treatment and its side effects. That way you'll be prepared to discuss it if your doctor recommends it as a cancer treatment option.

How does hormone therapy cancer treatment work?

Specific types of tumors — most commonly tumors of the breast and of the prostate — rely on hormones such as estrogen and testosterone to survive and grow. Hormone therapy is a cancer treatment that attacks these hormone-dependent tumors in two ways:

  1. Reducing hormones in your body. By reducing the level of estrogen or testosterone in your body, hormone therapy cuts off the supply of hormones your cancer relies on for its survival.
  2. Changing your cancer's ability to use hormones. Synthetic hormones can bind to your cancer's hormone receptors, blocking your cancer's ability to get the hormones it needs for growth.

By altering your cancer's hormone supply, hormone therapy can make your tumors shrink. This cancer treatment only works for hormone-sensitive cancers.

Who can benefit from hormone therapy cancer treatment?

If your cancer is hormone sensitive, you might benefit from hormone therapy as part of your cancer treatment. Your doctor can tell you whether or not your cancer is sensitive to hormones. This is usually determined by taking a sample of your tumor (biopsy) for analysis in a laboratory.

Cancers that are most likely to be hormone-receptive include:

  • Breast cancer
  • Prostate cancer
  • Ovarian cancer
  • Endometrial cancer

Not every cancer of these types is hormone-sensitive, however. That's why the cells of your cancer must be analyzed to determine if hormone therapy is appropriate for you.

Uses for Hormone Therapy Cancer Treatment

Hormone therapy is rarely used as a main (primary) cancer treatment. It's usually used in combination with other types of cancer treatments, including surgery, radiation and chemotherapy.

Your doctor might use a hormone therapy before you begin a primary cancer treatment, such as before surgery to remove a tumor. This is called neoadjuvant therapy. Hormone therapy can sometimes shrink a tumor to a more manageable size so that it's easier to remove during surgery.

Hormone therapy is sometimes given in addition to the primary treatment — usually after — in an effort to prevent the cancer from recurring (adjuvant therapy). If you've had surgery to remove your tumor and it appears that all of your cancer has been removed, your doctor might use hormone therapy to try to keep your cancer from coming back.

In some cases of advanced (metastatic) cancers, such as in advanced prostate cancer and advanced breast cancer, hormone therapy is sometimes used as the main treatment.

Researchers are also exploring the use of hormone therapies to prevent cancer from occurring in people with a high risk of cancer.

Types of Hormone Therapy

Hormone therapy can be given in several forms, including:

Surgery can reduce the levels of hormones in your body by removing the parts of your body that produce the hormones, including:

  • Testicles (orchiectomy or castration)
  • Ovaries (oophorectomy) in premenopausal women
  • Adrenal gland (adrenalectomy) in postmenopausal women
  • Pituitary gland (hypophysectomy) in women

Because certain drugs can duplicate the hormone-suppressive effects of surgery in many situations, drugs are used more often than surgery for hormone therapy. Also, because removal of the testicles or ovaries will limit an individual's options when it comes to having children, younger people are more likely to choose drugs over surgery.

Radiation is used to suppress the production of hormones. Just as is true of surgery, it's used most commonly to stop hormone production in the testicles, ovaries, and adrenal and pituitary glands. Your doctor might recommend radiation therapy rather than surgery if surgery is too risky for you or if it carries too many side effects.

Various drugs can alter your body's production of estrogen and testosterone. These can be taken in pill form or by means of injection. The most common types of drugs for hormone-receptive cancers include:

  • Anti-hormones
    Anti-hormones block your cancer cells' ability to interact with the hormones that propel your cancer's growth.  Though these drugs don't reduce your body's production of hormones, anti-hormones block your cancer's ability to use these hormones.  Anti-hormones include the anti-estrogens toremifene (Fareston) for breast cancer, and the anti-androgens flutamide (Eulexin) and bicalutamide (Casodex) for prostate cancer.
  • Aromatase inhibitors
    Aromatase inhibitors (AIs) target enzymes that produce estrogen in postmenopausal women, thus reducing the amount of estrogen available to fuel tumors.  AIs are only used in postmenopausal women because the drugs can't prevent the production of estrogen in women who haven't yet been through menopause.  Approved AIs include letrozole (Femara), anastrozole (Arimidex) and exemestane (Aromasin).  It has yet to be determined if AIs are helpful for men with cancer.
  • Luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists
    LH-RH agonists — sometimes called analogs — and LH-RH antagonists reduce the level of hormones in your body by altering the mechanisms in your brain that tell your body to produce hormones.  LH-RH agonists are essentially a chemical alternative to surgery for removal of the ovaries for women, or of the testicles for men.  Depending on your cancer type, you might choose this route if you hope to have children in the future and want to avoid surgical castration.  In most cases the effects of these drugs are reversible.

Examples of LH-RH agonists include:

  • Leuprolide (Lupron, Viadur, Eligard) for prostate cancer
  • Goserelin (Zoladex) for breast and prostate cancers
  • Triptorelin (Trelstar) for ovarian and prostate cancers

One LH-RH antagonist is currently approved for men with prostate cancer — abarelix (Plenaxis) — and is also under investigation for use in women with breast cancer.

Side Effects of Hormone Therapy

Most of the side effects of hormone therapy are temporary. However, surgery and radiation can cause permanent damage to your ovaries or testicles.

Common side effects in men undergoing hormone therapy include:

  • Decrease in sexual desire
  • Enlarged breasts
  • Hot flashes
  • Inability to achieve an erection
  • Incontinence
  • Osteoporosis

In women undergoing hormone therapy, side effects can include symptoms similar to those of menopause, such as:

  • Fatigue
  • Hot flashes
  • Mood swings
  • Nausea
  • Osteoporosis
  • Weight gain

Resistance to Hormone Therapy

If you opt for hormone therapy as a cancer treatment, be aware that the effects of hormone therapy may be limited. Most advanced hormone-sensitive cancers eventually become resistant to hormone treatment and find ways to thrive without hormones.

For instance, many women who've had surgery for breast cancer take certain hormone therapy drugs only for five years because taking it for a longer period doesn't offer any further benefit and may actually increase the risk that cancer will recur. But you're not out of options at the end of those five years. Your doctor may prescribe another form of hormone therapy to which your cancer may respond. Women who've taken tamoxifen, for example, may be able to take an aromatase inhibitor, such as letrozole.

If you have prostate cancer, your doctor might prescribe intermittent dosing of hormone therapy drugs in an attempt to prevent your cancer from becoming resistant to therapy. This means you won't take a drug continuously for several years. Instead you'll start and stop taking the drug as your doctor closely monitors your cancer.

Other Hormone Treatments for Cancer

Certain cancers produce excessive levels of hormones. Though rare, cancers such as carcinoid tumors, pheochromocytomas and other neuroendocrine cancers lead to production of these higher levels of your body's natural hormones. The excess hormones can cause such signs and symptoms as sweating, flushing, high blood pressure and diarrhea. Your doctor might prescribe hormone-blocking drugs to reduce these symptoms.

Deciding What's Best for You

Talk with your doctor about the potential side effects and the possible benefits of all the treatments you're considering. Balancing the risks with the benefits is the best way to choose a treatment that's best for you.


By Mayo Clinic Staff
March 2006



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