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Treatment Name: Anastrozole (Arimidex®)

Anastrozole (Arimidex®) is a Chemotherapy Regimen for Breast Cancer - early stage

How does anastrozole work?
Anastrozole is designed to inhibit an enzyme (a protein) in your body called aromatase. Aromatase is responsible for helping produce estradiol (a type of estrogen). When anastrozole inhibits aromatase, less estrogen is produced in the body, and less estrogen is able to bind to the receptors on breast cancer cells. Since certain breast cancer cells need estrogen to grow and divide, aromatase is given to prevent estrogen from being made.

Goals of therapy:
Anastrozole is commonly taken to prevent the cancer from coming back in the same breast or the other breast.


  • Usual starting dose: Anastrozole 1 mg oral tablet by mouth daily

Anastrozole is usually taken at home. Anastrozole therapy is often recommended to be taken for 3 to 5 years total. Anastrozole is only indicated for use in post-menopausal women and should not be used by pre-menopausal women.

Side Effects

In a multi-drug regimen, each medication has unique side effects. When these medicines are given together, drug-related side effects reported in clinical studies give the best estimate of what to expect. In clinical studies, the most commonly reported side effects with anastrozole are shown here. Side effects sometimes have percentage ranges [example 2 – 16%] because they differed between in clinical studies:

  • Hot flashes (34%)
  • Joint pain (28%)
  • Fatigue (2 - 16%)
  • Mood changes (16%)
  • Nausea or vomiting (11%)
  • Vaginal bleeding (5%)
  • Cataracts (4%)
  • Vaginal discharge (3%)
  • Heart attack (3%)
  • Stroke (1%)
  • Blood clots (3%)
  • Bone fractures (hip, spine, or wrist: 1 - 6%)
  • Endometrial cancer (0.1% = 1 in 1,000 patients)

*Anastrozole was associated with less hot flashes, vaginal discharge or vaginal bleeding, stroke, blood clots, and endometrial cancer, compared to tamoxifen. However, joint problems as well as bone fractures of the spine and wrist (not hip) were more common with anastrozole than with tamoxifen.

Side effect videos Side Effect Videos
PainPainFatigue Fatigue Nausea and VomitingNausea and VomitingBlood ClotsBlood Clots


How often is monitoring needed?
Labs (blood tests) may be checked before treatment and every one to three months thereafter as needed. Labs often include: Complete Blood Count (CBC), Comprehensive Metabolic Panel (CMP), triglycerides, and blood cholesterol levels.

How often is imaging needed?
Imaging may be checked before treatment and  as often as every two to six months during treatment. Imaging may include: bone scans, magnetic resonance imaging (MRI), and computerized tomography (CT) scans. DEXA (dual energy x-ray absorptiometry) scans may be performed to monitor your bone mineral density.

How might blood test results/imaging affect treatment?
Depending upon the results, your doctor may advise to continue anastrozole as planned, or delay or switch therapy.

ChemoExperts Tips

  • Ask your doctor before taking estrogen replacement therapy or other medications that contain estrogen as they may decrease the effectiveness of anastrozole
  • A pharmacist should ALWAYS review your medication list to ensure that drug interactions are prevented or managed appropriately
  • Clinical trials may exist for breast cancer. Ask your doctor if any studies are currently enrolling in your area. If not, go to to search for other centers offering study medications.

Patient Assistance & Co-payment Coverage

Patients under the age of 65 years, or those with private insurance plans:
If you have insurance and are looking for patient assistance or copay assistance for Anastrozole (Arimidex®), we have provided links that may help.

Visit our Patient Assistance page and click the links to various patient assistance programs for help paying for Anastrozole (Arimidex®). Depending upon your income, they may be able to help cover the cost of:

  • Anastrozole

For Branded medications (may be available for generic medications too), check with the manufacturer to determine if a co-pay card is offered and if it could reduce your monthly copay.

  • If you are uninsured, check with the manufacturer to determine if you are eligible to receive medication at no cost.

Medicare and Medicaid patients (Patients 65 years or older):
The clinic providing treatment will likely pre-authorize medications and immune therapies such as Anastrozole (Arimidex®) and are the best source to help you understand drug cost.

  • Ask to speak with a patient assistance technician or financial counselor at the clinic or hospital administering this therapy.

Emotional Wellness

What is Emotional Wellness?
Emotional wellness is having a positive outlook balanced with a realistic understanding of current life events. This requires both an awareness and acceptance of your emotions. It is with this knowledge that you can develop a plan to take the necessary actions to positively impact your life.

Emotional wellness uses an ongoing process to continually reflect on the stressors of life in a constructive manner to move forward and create happiness.

Because emotional wellness is deeply connected with physical, social, and spiritual wellness, pursuing it often becomes particularly difficult in times of major illness. Despite this difficulty, working toward emotional wellness has been connected to improved treatment outcomes and a higher likelihood of achieving goals of therapy.

Learn more about pursuing emotional wellness while receiving treatment with Anastrozole (Arimidex®)

Individual Drug Label Information

Anastrozole (Arimidex®)

  • Anastrozole is an oral tablet
  • Can be taken with or without food. Swallow tablets whole--do not crush
  • If you miss a dose, take it as soon as you remember if it’s the same day. If it is the next day, take your regular dose as scheduled. Do not double the dose to make up for the missed dose
  • Store at room temperature in a cool, dry place
  • Dosage adjustments may be required due to side effects
  • Notify your healthcare provider if you experience any tickling, tingling, or numbness
  • May cause fetal harm; avoid pregnancy
General Anastrozole (Arimidex) Side Effects
  • One of the most common side effects reported are hot flashes. Talk to your doctor about ways to minimize and treat hot flashes. Do not take any medicines, herbs, or natural supplements without speaking with your doctor or pharmacist first
  • Joint pain, back pain, general pain
  • Fatigue and weakness
  • Decreased bone strength and density, fractures
  • Increase in cholesterol in the blood
  • Nausea and vomiting
  • Increase risk of heart attack or chest pain in patients with a history of these problems
  • High blood pressure
  • Mood swings, depression, and insomnia
  • Headache
  • Fluid retention
  • Skin rash
  • Decreased sexual drive
  • Diarrhea or constipation
  • Click on the anastrozole (Arimidex) package insert below for reported side effects and possible drug interactions

Side Effect Videos
Nausea and VomitingNausea and VomitingDiarrheaDiarrheaFatigue Fatigue ConstipationConstipationPainPainBlood ClotsBlood Clots

See DailyMed package insert.

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1. Baum M, Budzar AU, Cuzick J, et al. Anastrozole alone or in combination with tamoxifen versus tamoxifen alone for adjuvant treatment of postmenopausal women with early breast cancer: first results of the ATAC randomised trial. Lancet. 2002;359:2131-2139.

2. Boccardo F, Rubagotti A, Puntoni M, et al. Switching to anastrozole versus continued tamoxifen treatment of early breast cancer: preliminary results of the Italian Tamoxifen Anastrozole Trial. J Clin Oncol. 2005;23:5138-5147.

Created: March 14, 2016 Updated: August 29, 2016

What is Breast Cancer - early stage?

What is Early Stage Breast Cancer?
A disease of either the milk-producing glands known as lobules, or milk ducts, or other cells found in the breast. Early stage breast cancer may also affect the lymph nodes, but has not usually spread to other areas of the body. Breast cancer is the most common type of cancer diagnosed in women, but may rarely affect men as well. Breast cancer cells may have increased expression of estrogen receptors (ER positive or negative), progestin receptors (PR positive or negative), and/or HER-2 receptors (HER-2 positive or negative). The presence or lack of these receptors will help determine the most effective chemotherapy medications to give.

Genetic causes, such as the BRCA (pronounced "Bracka") mutation, significantly increase the risk of developing breast cancer. Other risk factors for breast cancer include family history of breast cancer, high fat diet, and obesity. The stage of breast cancer can vary at diagnosis and throughout treatment. Stages of breast cancer include I, II, III, and IV. The effectiveness of the treatment may depend upon the stage at diagnosis.

Types of breast cancer:
1. Hormone-receptor positive or negative (60 - 65% of patients)

  • Estrogen Receptor positive (ER)+ or negative (ER)-
  • Progestin Receptor positive (PR)+ or negative (PR)-

2. Hormone Epidermal growth factor Receptor-2 (HER-2) positive or negative (20 - 25% of patients)

  • HER-2 + (positive)
  • HER-2 -  (negative)

3. Triple Negative (15 - 18% of patients)

  • ER- and PR- and (HER-2)-
NOTE: Treatment Options listed below are not all-inclusive. Other treatments may be available. ChemoExperts provides drug information and does not recommend any one treatment over another. Only your Doctor can choose which therapy is appropriate for you.

Clinical Studies

If you are interested in reading the clinical trials results, please click on references below:

1. Baum M, Budzar AU, Cuzick J, et al. Anastrozole alone or in combination with tamoxifen versus tamoxifen alone for adjuvant treatment of postmenopausal women with early breast cancer: first results of the ATAC randomised trial. Lancet. 2002;359:2131-2139.

2. Boccardo F, Rubagotti A, Puntoni M, et al. Switching to anastrozole versus continued tamoxifen treatment of early breast cancer: preliminary results of the Italian Tamoxifen Anastrozole Trial. J Clin Oncol. 2005;23:5138-5147.

What is a CBC?

A Complete Blood Count (CBC) is a frequently ordered blood test that tells clinicians the status of your: 1) White blood cell count, 2) Hemoglobin, and 3) Platelet count at the time the test was taken.

Common uses:
1) White blood cell count (WBC): is used to determine infection risk, or response to chemotherapy. Certain chemotherapy agents may harm our good infection-fighting cells. Sometimes chemotherapy may need to be delayed to allow these cells to recover.

2) Hemoglobin: is used to determine if someone is anemic. Anytime the hemoglobin is below 12 g/dL, the person is said to be anemic. Red blood cell transfusions, and sometimes iron can be given to restore the hemoglobin level, but anemia treatment should always aim at treating the underlying cause or condition.

3) Platelet count: is used to determine if the risk of bleeding is increased or if a platelet transfusion is required to prevent bleeding. Certain medications that increase bleeding risk, such as: aspirin, certain chemotherapy agents, and blood thinners, may need to be stopped temporarily until the platelet count is within a safe range.

What is a CMP?

A Comprehensive Metabolic Panel (CMP) is a frequently ordered blood test that tells clinicians the status of your: 1) Electrolytes & Acid/Base status2) Kidney function, 3) Liver function, 4) Blood sugar, and 5) Calcium at the time the test was taken. It is commonly used to monitor liver and kidney function when beginning new medications such as chemotherapy. A total of 14 tests are run simultaneously and are shown below.

Electrolytes & Acid/Base status:
1) Sodium, 2) Potassium, 3) Carbon dioxide, 4) Chloride

Kidney Function:
5) BUN (blood urea nitrogen), 6) Serum creatinine (Scr)

Liver Function:
7) AST, 8) ALT, 9) Total bilirubin, 10) Alk Phos, 11) Albumin, 12) Total protein

Blood sugar:
13) Serum glucose

14) Serum calcium