Breast Cancer Health Center

Hormone Therapy for Breast Cancer

What Are Common Hormone Drugs Used for Breast Cancer? continued...

Arimidex (anastrozole is the generic name) was initially approved for the treatment of advanced (stage IV) breast cancer in women who've gone through menopause and whose cancer has grown despite taking tamoxifen. It has replaced tamoxifen as the first-line therapy for postmenopausal women with hormone-positive or hormone-unknown locally advanced (stage III) or stage IV breast cancer. It is also approved as an add-on treatment of early hormone-positive breast cancer (stages I and II) in women who are postmenopausal. It is also taken in pill form.

Femara (also called letrozole) is approved for initial or follow-up treatment of hormone-sensitive locally advanced or metastatic breast cancer in women who have gone through menopause. It is taken in pill form, once each day.

Tamoxifen and raloxifene (marketed as Evista) are the only drug currently approved for breast cancer prevention in high-risk women. However, studies are under way to test whether the aromatase inhibitors can also be safely used for this purpose.

What Are the Side Effects of Hormone Therapy for Breast Cancer?

The side effects of tamoxifen therapy for breast cancer are similar to symptoms of menopause. The most common side effects are hot flashes, vaginal discharge, fluid retention, and swelling. Some women experience irregular menstrual periods, headaches, fatigue, nausea and/or vomiting, vaginal dryness or itching, irritation of the skin around the vagina, and skin rash. As is the case with menopause, not all women who take tamoxifen have these symptoms. Men who take tamoxifen may experience headaches, nausea and/or vomiting, skin rash, impotence, or a decrease in sexual interest.

There is evidence that tamoxifen therapy can increase the risk of cancer of the uterus in some women. Women taking tamoxifen should have a pelvic examination every year to look for any signs of cancer. Any vaginal bleeding, other than menstrual bleeding, should be reported to a doctor as soon as possible.

Tamoxifen therapy has been linked to an increased risk of blood clots, especially in women who are also taking chemotherapy. It can also interfere with other drugs you may be taking.

Raloxifene has similar side effects to tamoxifen, but to a lesser extent.

For Femara, the most common side effects are mild nausea and vomiting, tiredness, headaches, muscular aches, joint pain, and hot flashes that tend to eventually diminish or disappear. Some women may notice some hair thinning, but this is usually mild and goes back to normal at the end of treatment.

For Arimidex, common side effects include hot flashes, nausea, decreased energy and weakness, back pain, bone pain, increased cough, flu-like symptoms, swelling of the arms and legs, as well as joint pain and stiffness.

Both Femara and Arimidex are linked to increased bone loss. Bone density should be monitored while taking these drugs.

There are other hormone therapy drugs used to treat breast cancer. Most, such as Aromasin, Faslodex, and Fareston are used to treat metastatic breast cancer.