Hormone Therapy for Endometrial Cancer

This type of treatment uses hormones or hormone-blocking drugs to treat cancer. It’s not the same as the hormone therapy given to ease the symptoms of menopause (menopausal hormone therapy). It's most often used to treat endometrial cancer that's advanced (stage III or IV) or has come back after treatment (recurred). Hormone therapy is often used along with chemotherapy.

Hormone treatment for endometrial cancer can include:

• Progestins (This is the main hormone treatment used.)
• Tamoxifen
• Luteinizing hormone-releasing hormone agonists (LHRH agonists)
• Aromatase inhibitors (AIs)

At this time, no one type of hormone treatment has been found to be the best for endometrial cancer.

Progestins

The main hormone treatment for endometrial cancer uses progesterone or drugs like it (called progestins). The 2 most commonly used progestins are:

• Medroxyprogesterone acetate (Provera^®), which can be given as an injection or as a pill
• Megestrol acetate (Megace^®), which is given as a pill or liquid

These drugs slow the growth of endometrial cancer cells. They've been found to be useful in treating women with endometrial cancer who want to be able to get pregnant in the future, and this is an area of research interest.

Side effects can include:

• Hot flashes
• Night sweats
• Weight gain (from fluid retention and an increased appetite)
• Worsening of depression
• Increased blood sugar levels in women with diabetes
• Serious blood clots (this is rare)

Sometimes endometrial hyperplasia and early endometrial cancers can be treated with an intrauterine device (IUD) that contains a progestin called levonorgestrel. This may be combined with another hormone drug, like medroxyprogesterone acetate or a luteinizing hormone-releasing hormone agonist. (See below.)

Tamoxifen

Tamoxifen is an anti-estrogen drug often used to treat breast cancer. It might also be used to treat advanced or recurrent endometrial cancer. Alternating progesterone and tamoxifen is an option that seems to work well and be better tolerated than progesterone alone.

The goal of tamoxifen therapy is to keep any estrogens in the woman's body from boosting the growth of the cancer cells. Though tamoxifen may keep estrogen from "feeding" the cancer cells, it acts like a weak estrogen in other parts of the body. It doesn't cause bone loss, but it can cause hot flashes and vaginal dryness. Women taking tamoxifen also are at higher risk for serious blood clots in the legs.

Luteinizing hormone-releasing hormone agonists

Most women with endometrial cancer have had their ovaries removed as a part of treatment. Some women might have had radiation treatments that made their ovaries inactive. This helps keep the body from making estrogen and may also slow the growth of the cancer.

Luteinizing hormone-releasing hormone agonists (LHRH agonists) are drugs that lower estrogen levels in women who still have working ovaries. These drugs "turn off" the ovaries in women who are premenopausal so they don't make estrogen.

Goserelin (Zoladex^®) and leuprolide (Lupron^®) are drugs that might be used to treat endometrial cancer. They're given as a shot every 1 to 3 months. These drugs are also called gonadotropin-releasing hormone (GNRH) agonists.

Side effects can include any of the symptoms of menopause, such as hot flashes and vaginal dryness. They can also cause muscle and joint aches. If taken for a long time (years), these drugs can weaken bones, sometimes leading to osteoporosis.

Aromatase inhibitors

Even after the ovaries are removed (or are not working), estrogen is still made in fat tissue. This becomes the body's main source of estrogen. Drugs called aromatase inhibitors can stop this estrogen from being made and lower estrogen levels even further. Examples of aromatase inhibitors include letrozole (Femara^®), anastrozole (Arimidex^®), and exemestane (Aromasin^®). These drugs are most often used to treat breast cancer, but can be helpful in treating endometrial cancer, too. They're most often used to treat women who cannot have surgery, but doctors are looking at other ways these drugs could be helpful.

Side effects can include headaches, joint and muscle pain, and hot flashes. If taken for a long time (years), these drugs can weaken bones, sometimes leading to osteoporosis. These drugs are still being studied for how to best use them to treat endometrial cancer.