Femara (letrozole) is a potent, nonsteroidal aromatase inhibitor indicated for the adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer. It is also approved for the extended adjuvant treatment of early breast cancer following five years of tamoxifen therapy, as well as for the first-line treatment of advanced or metastatic breast cancer in postmenopausal women. By significantly suppressing estrogen synthesis, Femara targets the hormonal drivers of cancer proliferation, offering a targeted mechanism of action with a well-established efficacy and safety profile in clinical oncology.

Features

• Active ingredient: Letrozole 2.5 mg
• Pharmacologic class: Nonsteroidal aromatase inhibitor
• Administration: Oral tablet, once daily
• Bioavailability: Rapid and nearly complete (>99%)
• Half-life: Approximately 2 days
• Metabolism: Hepatic, via CYP3A4 and CYP2A6
• Excretion: Primarily renal (≥90%)
• FDA-approved indications: Adjuvant, extended adjuvant, and first-line metastatic treatment in postmenopausal women with hormone receptor-positive breast cancer

Benefits

• Significantly reduces the risk of cancer recurrence in early breast cancer when used as adjuvant therapy
• Improves disease-free survival and overall survival in well-defined clinical populations
• Offers a targeted mechanism with selective estrogen suppression, minimizing impact on other hormonal pathways
• Demonstrated efficacy in extending adjuvant settings after tamoxifen therapy
• Generally well-tolerated with a predictable side effect profile manageable for long-term use
• Convenient once-daily oral dosing supports adherence to long-term treatment regimens

Common use

Femara is primarily prescribed for the management of hormone receptor-positive breast cancer in postmenopausal women. Its most common application is as adjuvant therapy following primary treatment (surgery, with or without chemotherapy and radiation) to reduce the risk of cancer recurrence. It is also used in the extended adjuvant setting after patients have completed five years of tamoxifen therapy, further lowering recurrence risk. In advanced or metastatic disease, Femara serves as a first-line endocrine therapy, often providing disease control and symptomatic relief. Off-label uses may include ovulation induction in fertility treatments under specialist supervision, though this is distinct from its oncology indications.

Dosage and direction

The standard dosage of Femara is one 2.5 mg tablet taken orally once daily, with or without food. Treatment duration varies based on indication:

• Adjuvant treatment: Typically continued for 5 years.
• Extended adjuvant treatment: Administered for up to 5 years following 5 years of tamoxifen.
• Advanced/metastatic cancer: Continued until disease progression or unacceptable toxicity.

Tablets should be swallowed whole with water. Dosing does not require adjustment for age, but renal or hepatic impairment may necessitate careful monitoring. Treatment should be initiated and supervised by an oncologist. Adherence to the prescribed schedule is critical for therapeutic efficacy; use a pill organizer or reminder system if needed.

Precautions

• Bone mineral density: Femara accelerates bone loss. Baseline DEXA scan is recommended, with periodic monitoring and calcium/vitamin D supplementation. Consider bisphosphonates if osteopenia or osteoporosis develops.
• Cardiovascular health: Monitor lipid profiles and blood pressure; increased risk of hypercholesterolemia and cardiovascular events has been observed.
• Cognitive effects: Some patients report mild memory impairment or concentration issues.
• Hepatic/renal impairment: Use with caution in moderate to severe impairment; no formal dose adjustment but increased monitoring advised.
• Pregnancy contraindication: Femara is teratogenic. Must not be used in premenopausal women unless ovarian function is suppressed.
• Driving and operating machinery: Generally safe, but be cautious if experiencing dizziness or fatigue.

Contraindications

• Premenopausal women (unless in combination with ovarian suppression therapy)
• Pregnancy or women who may become pregnant
• Known hypersensitivity to letrozole or any excipients in the formulation
• Co-administration with estrogen-containing therapies

Possible side effect

• Very common (≥10%): Hot flashes, fatigue, arthralgia, myalgia, headache, hypercholesterolemia
• Common (1–10%): Nausea, sweating, edema, osteoporosis, fractures, dizziness, insomnia, weight increase
• Uncommon (0.1–1%): Vaginal bleeding, hair thinning, depression, tachycardia, thrombocytopenia
• Rare (<0.1%): Severe skin reactions, hepatitis, anaphylaxis

Most side effects are mild to moderate and often diminish over time. Musculoskeletal pain and vasomotor symptoms are the most frequently reported but rarely lead to discontinuation.

Drug interaction

• Estrogens: Concomitant use antagonizes Femara’s therapeutic effect; contraindicated.
• CYP3A4 inducers (e.g., rifampicin, carbamazepine): May reduce letrozole plasma concentrations.
• CYP2A6 inhibitors: Potential to increase letrozole levels, though clinical significance is unclear.
• Tamoxifen: Concurrent use reduces letrozole concentration; not recommended.
• Other anticancer therapies: Additive myelosuppression possible when combined with chemotherapy.

Missed dose

If a dose is missed, it should be taken as soon as remembered on the same day. If the day has passed, skip the missed dose and resume the usual schedule the next day. Do not double the dose to make up for a missed one. Consistent daily dosing is important for maintaining stable aromatase inhibition.

Overdose

No specific antidote exists for letrozole overdose. Reported cases are rare, and symptoms would be expected to be an exaggeration of known side effects (e.g., severe fatigue, dizziness). Provide supportive care, including monitoring of vital signs and symptomatic treatment. Dialysis is unlikely to be effective due to high protein binding. Contact a poison control center for management guidance.

Storage

Store at room temperature (15–30°C or 59–86°F) in the original container, protected from light and moisture. Keep out of reach of children and pets. Do not use after the expiration date printed on the packaging.

Disclaimer

This information is intended for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for personalized recommendations based on your health status and treatment history. Do not initiate or discontinue Femara without medical supervision.

Reviews

Clinical oncologist, 15 years of experience: “In my practice, Femara has been a cornerstone of adjuvant hormonal therapy. Its efficacy in reducing recurrence is well-substantiated by trials like BIG 1-98. Tolerability is generally good, though I proactively manage bone health with supplements and monitoring.”

Patient, 4 years on therapy: “The hot flashes and joint stiffness were challenging initially, but they improved after the first few months. Knowing it significantly lowers my risk of recurrence makes it worth it. Easy to take, and my follow-up scans have been clear.”

Oncology pharmacist: “Letrozole’s once-daily dosing and generally predictable profile make it a manageable long-term therapy for most patients. Key counseling points include adherence, bone health, and reporting persistent musculoskeletal symptoms.”

Clinical trial data: Meta-analyses consistently show a significant improvement in disease-free survival (HR 0.85) and overall survival in high-risk subgroups when compared to tamoxifen. The benefit is particularly pronounced in women with higher risk of recurrence.