Which is better - Aromasin or Femara?
Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on July 15, 2020.
Aromasin (generic name: exemestane) and Femara (generic name: letrozole) are both aromatase inhibitors (AI) used for the treatment of breast cancer in women, but they have slightly different approved uses. A study called the FATA-GIM3 clinical trial compared Aromasin and Femara use in early breast cancer, and investigators found the two drugs worked equally well.
In the FATA-GIM3 clinical trial:
- Aromasin 25 mg per day resulted in a 5-year disease-free survival rate of 88%, but ranged between 85.8% and 89.9% of women.
- Femara 2.5 mg per day led to a 5-year disease-free survival rate in 89.4%, with a range between 87.3% to 91.1% of women.
Survival rate is the number of patients still alive at the conclusion of a study. The results were similar with no statistical differences. In addition, 5 years of treatment with aromatase inhibitors was not superior to 2 years of tamoxifen followed by 3 years of an aromatase inhibitor.
The American Cancer Society also states that Femara and Aromasin work about equally well in treating breast cancer.
Some women may decide, in conjunction with their physician, to extend aromatase inhibitor therapy for up to 10 years, particularly if they are at a higher risk for another breast cancer. As noted by American Society of Clinical Oncology (ASCO), extending aromatase inhibitor treatment is not associated with an overall survival advantage but can lower the risk for breast cancer returning and occurring in the opposite breast, compared to no treatment (placebo). ASCO does not recommend extended treatment for longer than 10 years.
Which aromatase inhibitor is best?
The type and length of treatment for breast cancer should always be an individual decision made by a patient and their health care provider. Selecting a drug treatment based on your type of breast cancer and former treatments you have used, or side effects you have experienced, is important. When selecting an aromatase inhibitor for treatment, you may also want to discuss other important factors with your doctor, such as possible side effects, availability and cost.
There are three aromatase inhibitors available in the U.S. They are all approved as treatments for early, locally advanced or metastatic breast cancer.
- Arimidex (anastrozole)
- Aromasin (exemestane)
- Femara (letrozole).
Aromatase inhibitors all work the same way by stopping estrogen production in your body by blocking the enzyme known as aromatase. Estrogen can help to fuel the growth of breast cancer.
Is either Femara or Aromasin recommended in breast cancer treatment guidelines?
Aromatase inhibitors (AIs), such as Aromasin and Femara are standard, ASCO guideline recommended treatment as adjuvant therapy in early stage breast cancer in postmenopausal women. “Adjuvant treatment” is when additional treatments are given after your first breast cancer treatment, such as surgery, chemotherapy or radiation, to lower the risk of the cancer coming back.
AIs are also used in the treatment of advanced or metastatic breast cancer. Postmenopausal women with metastatic, HR+ positive breast cancer should be offered AIs as first-line endocrine therapy, based on ASCO guidelines.
How do Aromasin and Femara compare?
Here’s a summary of some of the main similarities and differences between Aromasin and Femara.
- Both drugs are approved to treat early and late breast cancer, however, in slightly different ways.
- They are both tablets that you swallow by mouth once a day. Aromasin comes as a 25 mg tablet and Femara comes as a 2.5 mg tablet.
- Aromasin should be taken after a meal, but Femara can be taken with or without food.
- With either medicine, you’ll continue treatment as long as your doctor recommends.
Aromasin is FDA-approved in postmenopasual women for:
1. The treatment of early breast cancer (cancer that has not spread outside the breast) in women who:
- have cancer that needs the female hormone estrogen to grow, and
- have had other treatments for breast cancer, and
- have taken tamoxifen for 2 to 3 years, and
- are switching to Aromasin to complete 5 years in a row of hormonal therapy.
2. Advanced breast cancer (cancer that has spread) after treatment with tamoxifen, and it did not work or is no longer working.
Femara is FDA-approved in postmenopausal women for:
1. Adjuvant treatment of hormone-receptor positive early breast cancer.
2. Extended, 5 to 10 year treatment of women with early breast cancer who have previously received tamoxifen therapy.
3. As the first or second treatment option for hormone-receptor positive or unknown advanced breast cancer.
Are the side effects with Aromasin and Femara the same?
Aromasin and Femara have both similar and different side effects. Some patients may tolerate one drug better than the other, and it is reasonable to consider switching between agents if one drug is poorly tolerated.
For example, side effects that can occur with both drugs include:
- Muscle and joint pain or stiffness
- Hot flashes (sudden sweating and feeling of warmth)
- Feeling tired
- Increased risk of osteoporosis (bone thinning) and fracture due to reduction in bone mineral density (BMD)
- Harm to an unborn baby
Other common side effects that can occur with Femara include: edema (fluid retention), dizziness, weight increase, and higher cholesterol levels. For a full listing of common and serious side effects, visit: Femara Side Effects
Other common side effects that can occur with Aromasin include: trouble sleeping and increased appetite. For a full listing of common and serious side effects, visit: Aromasin Side Effects.
These are not all the possible side effects of Aromasin or Femara. Call your doctor for medical advice about side effects.
Which is cheaper - Aromasin or Femara?
The brand name products Aromasin and Femara are both expensive medicines, costing in the hundreds of dollars per month. However, generic alternatives are available for both medications. Generic drugs will help to lower your prescription costs.
Insurance will most likely cover an aromatase inhibitor but your copays will be dependent upon your insurance plan. Contact your insurance company to check your drug coverage.
If you are paying cash, online discount coupons can be beneficial in lowering your costs.
- In general, letrozole, the generic for Femara, ranges about $15 to $70 per month for 30 of the 2.5 mg tablets.
- Exemestane, the generic for Aromasin, ranges from $50 to $180 per month for 30 of the 25 mg tablets.
- These prices are estimates based on online coupon discounts, and can vary based on location, pharmacy and coupon source.
- If you are having trouble affording your medication, the manufacturers of the brand name products may be able to offer assistance. Also, speak with your pharmacist and doctor about drug prices before you get your prescription.
Visit the Drugs.com Price Guide for more information.
- Researchers that compared Aromasin and Femara used in early breast cancer found that the two drugs worked equally well.
- With Aromasin, 88% of women lived for at least 5 years without their breast cancer returning, while 89.4% of women taking Femara lived for at least 5 years without their breast cancer returning. Statistically, there was no difference between these rates.
- Aromatase inhibitors have similar and different side effects. Similar side effects between the two treatments include: risk of bone thinning, hot flashes and sweating, tiredness and muscle and joint pain.
- Both drugs are available in less expensive generic forms and are usually covered on insurance plans.
This is not all the information you need to know about Aromasin or Femara for safe and effective use. Review the full product information for Aromasin or Femara here, and discuss this information with your doctor or other health care provider.
- De Placido S, Gallo C, De Laurentiis M, et al. Adjuvant anastrozole versus exemestane versus letrozole, upfront or after 2 years of tamoxifen, in endocrine-sensitive breast cancer (FATA-GIM3): a randomised, phase 3 trial [published correction appears in Lancet Oncol. 2018 Apr;19(4):e184]. Lancet Oncol. 2018;19(4):474-485. doi:10.1016/S1470-2045(18)30116-5. Accessed July 14, 2020.
- Up to Date. Pritchard K, et al. Adjuvant endocrine therapy for postmenopausal women with hormone receptor-positive breast cancer. Accessed July 14, 2020 at https://www.uptodate.com/contents/adjuvant-endocrine-therapy-for-postmenopausal-women-with-hormone-receptor-positive-breast-cancer
- American Cancer Society (ACS). Hormone Therapy for Breast Cancer. Accessed July 15, 2020 at https://www.cancer.org/cancer/breast-cancer/treatment/hormone-therapy-for-breast-cancer.html
- Aromatase Inhibitors. Susan G Komen. Online. Accessed July 15, 2020 at https://ww5.komen.org/BreastCancer/AromataseInhibitors.html
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