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Treatment Name: Letrozole (Femara®)

Letrozole (Femara®) is a Treatment Regimen for Breast Cancer - early stage

How does letrozole work?
Letrozole is designed to block an enzyme (a type of protein) in your body called aromatase. Aromatase is responsible for helping produce a female hormone known as estradiol (a type of estrogen).

When letrozole inhibits aromatase, there is less estrogen produced. When estrogen is not able to bind to the receptors on breast cancer cells, the cancer cells are not able to grow or divide. Patients with breast cancer that are not estrogen-receptor positive rarely respond to treatment with letrozole.

Goals of therapy:
Letrozole is commonly taken to maintain remission, prevent recurrence of breast cancer and increase the likelihood of cure.


  • Usual starting dose: Letrozole 2.5 mg oral tablet by mouth Once Daily

Letrozole is usually taken at home.

Letrozole is usually taken for five years after surgery, unless tamoxifen therapy was previously taken. If tamoxifen was given prior to starting letrozole, then letrozole is commonly taken to complete a total of 5 years of therapy with tamoxifen and letrozole.

Letrozole is only indicated for use in post-menopausal women and should not be used by pre-menopausal women.

Note: Individual doses may vary based upon your Doctor's recommendation, or drug availability


How often is monitoring needed?
Labs (blood tests) may be checked every one to three months. 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 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 letrozole as planned, reduce the dose, or delay or switch therapy.

ChemoExperts Tips

  • Unless specifically discussed with your doctor, avoid estrogen replacement therapy or other medications that contain estrogen as they may decrease the effectiveness of letrozole
  • 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 Letrozole (Femara®), 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 Letrozole (Femara®). Depending upon your income, they may be able to help cover the cost of:

  • Letrozole

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 Letrozole (Femara®) 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 Letrozole (Femara®)

Individual Drug Label Information

Letrozole (Femara®)

  • Letrozole is an oral tablet 
  • Letrozole can be taken with or without food. Swallow tablets whole and do not crush tablets. If you miss a dose, take the dose as soon as you remember if it is still the same day. If it is the next day, take your regular dose as scheduled. Do not double your dose to make up for the missed dose 
  • Letrozole should be stored at room temperature in a cool, dry place 
  • Dosage adjustments may be required due to side effects or liver dysfunction 
  • May cause fetal harm; avoid pregnancy 
General Letrozole (Femara) Side Effects 
  • One of the most common side effects reported is 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 
  • Decreased bone strength 
  • Increase in blood cholesterol 
  • May cause dizziness and/or drowsiness 
  • High blood pressure 
  • Increase risk of blood clots 
  • Mood swings 
  • Fluid retention 
  • Skin rash 
  • Decreased sexual drive 
  • Nausea and vomiting 
  • Constipation
  • Click on the letrozole (Femara) package insert below for reported side effects and possible drug interactions

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

See DailyMed package insert.

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Thürlimann B, Keshaviah A, Coates AS, et al. A comparison of letrozole and tamoxifen in postmenopausal women with early breast cancer. N Engl J Med. 2005;353:2747-2757.

Created: February 20, 2016 Updated: February 20, 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.

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

What does "Cure" mean?

The word “cure” means there are no cancer cells left in the body and cancer will never come back. Depending on the cancer type and stage, this may be the true goal of therapy. However, it is very difficult to prove all cancer cells are gone. Even though images, like X-rays and MRI’s, and blood tests may not show any signs of cancer, there can be a small amount of cancer cells still left in the body. Because of this, doctors use the word “remission” is used more often. This means there are no signs or symptoms of cancer. Patients in remission are followed closely for any signs of cancer returning. Sometimes, more chemotherapy may be given while in remission to prevent the cancer from coming back.

Doctors usually do not consider a patient “cured” until the chance of cancer returning is extremely low. If cancer does return, it usually happens within 5 years of having a remission. Because of this, doctors do not consider a patient cured unless the cancer has not come back within 5 years of remission. The five-year cutoff does NOT apply to all cancers.