Letrozole, known by the brand name Femara, is primarily prescribed for treating certain types of breast cancer in postmenopausal women. It functions as an aromatase inhibitor, reducing estrogen levels in the body to slow the growth of hormone-sensitive tumors. While its primary use is in cancer treatment and, off-label, for infertility, the relationship between letrozole and weight changes is worth exploring. This article delves into the uses of letrozole, its potential side effects (including weight changes), its off-label application for infertility, and other essential information.
What is Letrozole (Femara)?
Femara is an oral tablet containing the active ingredient letrozole. It belongs to the aromatase inhibitors drug class, a type of hormone therapy for breast cancer. Letrozole is a prescription medication approved by the Food and Drug Administration (FDA) for use in females who have gone through menopause.
Uses for Breast Cancer
Femara is prescribed for females with specific forms of early or advanced breast cancer. In early breast cancer, the cancer hasn't spread beyond the breast or armpit lymph nodes. Advanced breast cancer, on the other hand, has spread to nearby areas, lymph nodes (locally advanced), or other parts of the body (metastatic).
Femara is used in several ways for early HR+ breast cancer:
- Adjuvant treatment: Given after surgery to lower the risk of cancer recurrence.
- Extended adjuvant treatment: Administered after surgery and 5 years of tamoxifen treatment to further reduce the risk of recurrence.
For advanced breast cancer (HR+ or unknown hormone receptor status), Femara serves as:
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- First-line treatment: The initial drug used to treat advanced breast cancer.
- Second-line treatment: Used when past therapies have been ineffective, treating cancer that has returned or spread.
Off-Label Use for Infertility
Femara is also used off-label to treat infertility, particularly when it's caused by ovulation problems, such as those associated with polycystic ovary syndrome (PCOS). Off-label use means using an approved drug to treat a different condition.
Understanding Potential Side Effects
Femara, like all medications, can cause side effects. These can range from mild to severe, and it's important to be aware of them.
Mild Side Effects
More common mild side effects include:
- Hot flashes
- Flushed skin
- Increased sweating
- Joint pain
- Weakness
- Edema (swelling), particularly in ankles or feet
- Headache
- Dizziness
- Bone pain
Less common mild side effects can include:
- Fatigue
- Nausea
- Vaginal bleeding or spotting
- Changes in mood
Most of these side effects are temporary, resolving within a few days or weeks. However, if they worsen or persist, consulting a doctor or pharmacist is recommended.
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Serious Side Effects
Although less common, serious side effects can occur. Immediate medical attention is necessary if you experience any of the following:
- Reduced bone mineral density (weakened bones)
- Increased cholesterol level
- Severe allergic reaction
Side Effect Details
Reduced Bone Mineral Density: Femara can lower estrogen levels, which can weaken bones, increasing the risk of fractures. Doctors may monitor bone mineral density and prescribe medication to strengthen bones if needed.
Allergic Reaction: While rare, allergic reactions can occur. Mild symptoms include skin rash, itchiness, and flushing. Severe symptoms like swelling, difficulty breathing, and throat swelling require immediate medical attention.
Fatigue or Dizziness: Some individuals may experience fatigue or dizziness. It's crucial to avoid driving or operating machinery until you know how the drug affects you.
Weight Gain or Weight Loss: Body weight changes can occur during Femara treatment. Clinical studies have reported both weight gain and weight loss in people taking Femara for breast cancer. Cancer and its treatments can affect appetite and weight.
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Weight Changes: What to Expect
During clinical studies, both weight gain and weight loss were reported in people who took Femara for breast cancer treatment.
It's important to note that both cancer and cancer treatments can often cause changes in appetite and body weight. If you have questions or concerns about changes in your weight, it's best to consult with your doctor or pharmacist. They can help you understand the potential causes and recommend strategies for managing your weight.
Side Effects After Stopping Femara
Stopping Femara treatment typically doesn't cause side effects, and gradual cessation isn't necessary. In certain cases, a "withdrawal response" (hormonal shift) from stopping Femara may improve breast cancer if the drug has stopped working.
Letrozole for Infertility: An Off-Label Use
Femara is used off-label to treat infertility in females, particularly when infertility is caused by problems with ovulation (the release of eggs from your ovaries). The most common cause of ovulation problems that result in infertility is polycystic ovary syndrome (PCOS). Femara is used to treat infertility by inducing (causing) ovulation.
How Letrozole Induces Ovulation
For infertility treatment, Femara is taken for a few days after the start of your period. This temporarily lowers your estrogen level, signaling your pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These hormones stimulate an egg in your ovary to mature and be released, causing ovulation.
If you're already ovulating, Femara may cause more eggs than usual to mature and be released, a condition called controlled ovarian hyperstimulation or superovulation.
Dosage and Administration for Infertility
The typical dosage for inducing ovulation is 2.5 mg taken orally once daily for 5 days, starting on day 3 or day 5 of your menstrual cycle. Sometimes, a higher dosage (5 mg or 7.5 mg) may be recommended. Ovulation usually occurs 5 to 10 days after the last tablet.
Side Effects When Using Femara for Infertility
Side effects can include dizziness, fatigue, hot flashes, breast tenderness, mood swings, night sweats, nausea, vomiting, spotting, ovarian cysts, and rarely, ovarian hyperstimulation syndrome (OHSS).
Femara vs. Clomid
Femara (letrozole) and Clomid (clomiphene) are both used to induce ovulation. While Clomid has been discontinued, generic versions of clomiphene are still available. Studies comparing the two drugs have found slightly differing results. A 2023 study found Femara to be more effective than clomiphene in treating infertility in people with PCOS. A 2019 review of studies also found Femara to be more effective than clomiphene in treating infertility in females with PCOS. Another 2019 review of studies found Femara and clomiphene to be similarly effective in treating unexplained infertility.
Additional Information
Brand Name
Letrozole is the active drug in Femara. Generic forms of Femara are available.
Prescription Required
Yes, letrozole is available only with your doctor's prescription.
Precautions
It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects. Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment with this medicine and for at least 3 weeks after your last dose. If you think you have become pregnant while using the medicine, tell your doctor right away. This medicine may decrease bone mineral density when used for a long time. A low bone mineral density can cause weak bones or osteoporosis. If you have any questions about this, talk to your doctor. This medicine may increase the amount of cholesterol and fat in the blood. If this happens, your doctor may give you medicine to lower the cholesterol and fat in the blood. This medicine may make you dizzy, drowsy, or tired than they are normally. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
Drug Interactions
Using this medicine with any of the following medicines is not recommended: Bacillus of Calmette and Guerin Vaccine, Live, Dengue Tetravalent Vaccine, Live, Measles Virus Vaccine, Live, Mumps Virus Vaccine, Live, Rubella Virus Vaccine, Live, Smallpox Monkeypox Vaccine, Typhoid Vaccine, Varicella Virus Vaccine, Live, Yellow Fever Vaccine.
Other Medical Problems
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially: Bone problems (eg, osteoporosis) or Hypercholesterolemia (high cholesterol or fat in the blood)âUse with caution. May make these conditions worse. Cirrhosis or Liver disease, severeâUse with caution. The effects may be increased because of slower removal of the medicine from the body.
Proper Use
Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. You may take this medicine with or without food.
Missed Dose
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Storage
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing. Keep out of the reach of children. Do not keep outdated medicine or medicine no longer needed. Ask your healthcare professional how you should dispose of any medicine you do not use.
The Link Between Weight and Breast Cancer Treatment
Many women gain weight during breast cancer treatment due to the shock of diagnosis, life disruption, treatment stress, and reduced physical activity. Overweight or weight gain in breast cancer patients is concerning because it's linked to worse outcomes and increased recurrence risk.
Lifestyle Intervention and Weight Loss
A telephone-based lifestyle intervention (LI) led to significant weight loss that was still evident at 24 months, without adverse effects on QOL, hospitalizations, or medical events. Weight loss was greatest in those with higher baseline levels of moderate-intensity physical activity or improvement in QOL.
Recommendations for Women with Breast Cancer
If youâve been diagnosed with breast cancer, try to make exercise and a healthy diet part of your daily routine, especially if youâre overweight. It may be hard to make these kinds of changes if youâre struggling to recover from treatment. Some women say it helps to think of eating well and exercising as important parts of their treatment plans. As this study suggests, it seems to be easier to make diet and exercise changes if you have someone to talk to you and motivate you. Itâs also a good idea to talk to your primary care doctor and your surgeon before you start an exercise program. Tell them the exercises you plan to do and ask if there are any movements you should avoid or if you should limit your range of motion in any way. Losing weight is hard to do. But it can be done with careful diet and exercise changes. In the Breastcancer.org Nutrition section, the Eating to Lose Weight After Treatment pages can help you assess your weight and create a healthy eating plan.