What you can expect

By Mayo Clinic Staff

There are several approaches to hormone therapy.

Medications that block hormones from attaching to cancer cells

One approach to hormone therapy is to stop the hormones from attaching to the cancer cells. When the hormones can't access the cancer cells, the tumor growth may slow and the cells may die.

Breast cancer medications that have this action include:

  • Tamoxifen. Tamoxifen is usually taken daily in pill form. It's used to reduce the risk of cancer recurrence in women who have been treated for early-stage breast cancer. In this situation, it's typically taken for five to 10 years.

    Tamoxifen may also be used to treat cancer in women with advanced cancer. Tamoxifen is appropriate for both premenopausal women and postmenopausal women.

  • Toremifene (Fareston). Toremifene is taken as a daily pill. It's used to treat breast cancer that has spread to other areas of the body. Toremifene is approved for use in postmenopausal women.
  • Fulvestrant (Faslodex). Fulvestrant is administered as a shot every two weeks. It's used in postmenopausal women to treat advanced breast cancer in situations where other hormone therapies are no longer working.

Medications that stop the body from making estrogen after menopause

Aromatase inhibitors are a class of medicines that reduce the amount of estrogen in your body, depriving breast cancer cells of the hormones they need to grow and thrive.

Aromatase inhibitors are used in women who have undergone menopause.

Aromatase inhibitors used to treat breast cancer include:

  • Anastrozole (Arimidex). Anastrozole is used to reduce the risk of cancer recurrence in women who have been treated for early-stage breast cancer. It can also be used to treat advanced breast cancer.
  • Exemestane (Aromasin). Exemestane is used to reduce the risk of cancer recurrence in women who have been treated for early-stage breast cancer. It's sometimes used after taking tamoxifen for two or three years. It can also be used to treat advanced breast cancer in women for whom tamoxifen is no longer working.
  • Letrozole (Femara). Letrozole is used to reduce the risk of cancer recurrence in women who have been treated for early-stage breast cancer. It can be used alone or given after completing tamoxifen treatment. Letrozole is also used to treat advanced breast cancer.

Aromatase inhibitors are given as pills you take once a day. How long you continue aromatase inhibitors depends on your specific situation.

Treatments to stop ovarian function in premenopausal women

Women who haven't undergone menopause — either naturally or as a result of cancer treatment — may opt to undergo treatment to stop their ovaries from producing hormones. These strategies are generally used in women with advanced breast cancer.

Options may include:

  • Surgery to remove the ovaries (oophorectomy)
  • Radiation therapy aimed at the ovaries
  • Treatment with goserelin (Zoladex)

Treatments to stop ovarian function may allow premenopausal women to take medications only available to postmenopausal women.

Feb. 20, 2014