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Cancer Treatment Centers of America

Anastrozole (Arimidex®)


Brand Name: Arimidex®

Anastrozole is a breast cancer medication. Given alone or in combination with other treatments, such as surgery or radiation, anastrozole is used to treat early-stage breast cancer in postmenopausal women. This medication may also be given to postmenopausal women as a first treatment for breast cancer that has spread either within the breast or elsewhere in the body. It may also be a treatment option for women whose breast cancer has progressed after treatment with tamoxifen. Less commonly, anastrozole may be used to prevent breast cancer in women who are at high risk of developing this disease.

Anastrozole is a nonsteroidal aromatase inhibitor. It works by blocking aromatase, an enzyme that causes increased levels of estrogen in postmenopausal women. As a result, estrogen levels in the body are decreased, and the growth of cancer cells that rely on estrogen is either stopped or slowed.

This medication is taken as a tablet by mouth. Most commonly, anastrozole is taken once daily with or without food, and may be prescribed for long-term use, even for several years or longer. Be sure to follow the prescription and do not stop taking anastrozole before speaking with your doctor.

Anastrozole side effects

To prevent problematic interactions between anastrozole and other drugs, be sure to tell your doctor if you are allergic to any medications, and what other medications and supplements you are currently taking. Importantly, inform your doctor of any medications that contain estrogen, such as hormone replacement therapy, hormonal contraceptives, raloxifene, and tamoxifen.

Anastrozole may worsen or cause osteoporosis. Your doctor can discuss the risks of this medication, and ways to help decrease the risk of osteoporosis. Also be sure to inform your doctor if you have or ever had high cholesterol, liver disease, or heart disease.

Anastrozole should only be taken by postmenopausal women who cannot become pregnant. Tell your doctor if you are pregnant or breastfeeding before you begin taking this medication.

Possible side effects of anastrozole may include:

  • Weakness
  • Headache
  • Hot flashes
  • Sweating
  • Stomach pain
  • Nausea
  • Loss of appetite
  • Constipation
  • Diarrhea
  • Heartburn
  • Weight gain
  • Pain in the joints, bone, muscle or breasts
  • Mood swings or depression
  • Difficulty sleeping
  • Vaginal dryness or bleeding
  • Pain or tingling in the hands or feet
  • Dry mouth
  • Hair thinning

Call your doctor immediately if you experience any of anastrozole’s potentially serious side effects:

  • Chest pain
  • Sore throat, cough, fever, chills, swollen glands, or other signs of infection
  • Swelling, redness or warmth in hands or arms
  • Difficult, painful, or urgent urination
  • Blurry vision
  • Yellowing of the skin or eyes
  • Rash, hives, itching
  • Shortness of breath
  • Difficulty swallowing or breathing
  • Swelling of the eyes, face, lips, tongue, throat, arms, hands, feet, ankles, or lower legs

Please note that this is not a comprehensive list. Patients may experience additional effects not mentioned above.

At Cancer Treatment Centers of America (CTCA), your team of cancer experts will explain each of the side effects of anastrozole with you in detail, as well as the side effects and expectations of all other medications planned as part of your individualized treatment plan.

Anastrozole for cancer treatment

Anastrozole is approved by the FDA for the following cancer treatments:

  • Adjuvant (post-surgery) treatment of postmenopausal women with hormone receptor-positive early breast cancer
  • First-line treatment of postmenopausal women with hormone receptor-positive or hormone receptor-unknown locally advanced or metastatic breast cancer
  • Treatment of advanced breast cancer in postmenopausal women whose disease has progressed following treatment with tamoxifen

At Cancer Treatment Centers of America (CTCA), our integrative approach to cancer treatment works to fight your disease on all fronts and ensures that you remain at the center of everything we do. We encourage participation from both you and your family to make certain you are comfortable with all decisions made regarding your treatment.

The information provided here is for educational purposes only. In no way should it be considered as offering medical advice. Cancer Treatment Centers of America assumes no responsibility for how this material is used. Please check with a physician if you suspect you are ill. Also note that while Cancer Treatment Centers of America frequently updates its contents, medical information changes rapidly. Therefore, some information may be out of date.