What is hormone therapy?

Hormones are chemicals made by glands, like the thyroid, pancreas, adrenal glands, ovaries and testicles. Hormones help some types of cancer cells grow. Some cancers that might be sensitive to hormones and be treated with hormone therapy include breast, prostate, thyroid, endometrial, and adrenal cancers. Hormone therapy can make the cancer cells grow more slowly or stop them from growing.

As a cancer treatment, hormone therapy may mean taking medicines that block the activity of the hormone, stop the body from making the hormone, or change the hormone so it doesn't work like it should. Sometimes hormone therapy involves surgically removing the gland that's making the hormones.

How does hormone therapy work?

If you have a kind of cancer that may be hormone responsive, your healthcare provider will test the tumor for the presence of hormone receptors. The test helps predict whether your cancer is likely to respond to hormone therapy or hormone blockers.

Hormone receptor tests measure the amount of certain proteins (called hormone receptors) in or on cancer cells. Hormones that are naturally made in the body (like estrogen and progesterone) can attach to these proteins on the cancer cells and help them grow. If the test is positive, the hormone is probably helping the cancer cells to grow. In this case, hormone therapy may be helpful. If the test is negative, the hormone does not affect the growth of the cancer cells. Other cancer treatments will be used instead. Always talk with your healthcare provider about the results of the hormone receptor test.

If tests show that hormones are affecting your cancer, the cancer may be treated in 1 of these ways:

• Medicines that block the receptors so the cancer cells can't use the hormones they need to grow

• Medicines that keep the glands from making hormones

• Surgery to remove the glands that make the hormones

The type of hormone therapy and dose a person gets depends on many factors, such as:

• The type of cancer

• The stage of cancer

• The age of the person

• The risk of the cancer coming back

• The presence of hormone receptors on the tumor cells

When is hormone therapy given?

You may get hormone therapy before or after other cancer treatments. If hormone therapy is given before the primary treatment, it's called neoadjuvant treatment. These treatments help to shrink a tumor. They also help make the primary therapy, which is often surgery, work better. If hormone therapy is given after the primary treatment, it's called adjuvant treatment. Adjuvant therapy is done to help keep the cancer from coming back.

Hormone therapy might be a choice if you're not healthy enough to have surgery or other cancer treatments. It can help ease problems caused by the cancer.

Getting hormone therapy

Hormone therapy may be given in these ways:

• Pills or liquid. Many of these medicines are pills you take at home.

• Injections. Some hormone therapy medicines are given as shots. How often you get them depends on the medicine. It may be anywhere from once a month to once every 6 months.

• Surgery. In some cases, surgery is done to take out the organ or gland that makes the hormones that the cancer cells use to grow. For instance, for breast cancer, the ovaries can be taken out so they can't make estrogen. Or for prostate cancer, the testicles might be removed so they can't make testosterone.

What are the side effects of hormone therapy?

Below are some side effects that may be linked to hormone therapy. Side effects will vary depending on the type of hormone therapy that's given. Every person's response to hormone therapy is different, and not every person will have the same side effects. Talk with your healthcare provider about the possible side effects of your hormone therapy.

Some common side effects include:

• Hot flashes

• Nausea

• Vomiting

• Bone loss (osteoporosis) and higher risk for bone fractures

• Headaches

• Mood changes

• Diarrhea

• Skin rash

• Weight gain

• A loss of desire for sex

• Fatigue

• Loss of muscle mass

• In females:

  • Vaginal spotting (blood-stained discharge from the vagina that's not part of the regular menstrual cycle)

  • Irregular periods

  • Vaginal dryness, itching, or irritation of the skin around the vagina

• In males:

  • Trouble getting an erection (erectile dysfunction)

  • Breast enlargement

Other more serious but less common side effects include:

• In females, a higher risk of endometrial cancer (cancer of the lining of the uterus) and uterine sarcoma (cancer of the muscular wall of the uterus)

• Blood clots

• Stroke

• Eye problems, such as cataracts

• Liver toxicities