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Daily pills that stop the body making oestrogen after menopause, the backbone of hormone therapy for most breast cancers.
Non-steroidal (letrozole, anastrozole) and steroidal (exemestane) aromatase inhibitors block conversion of androgens to oestrogens in fat and tumour tissue. Superior to tamoxifen for postmenopausal women in adjuvant (ATAC, BIG 1-98) and metastatic settings; the standard partner for CDK4/6 inhibitors in first-line metastatic disease. Used with ovarian suppression in premenopausal women (SOFT/TEXT). Arthralgia, bone loss, and vaginal dryness drive non-adherence.
Competitive (letrozole, anastrozole) or irreversible (exemestane) inhibition of CYP19A1 aromatase. Connects to Estrogen receptor (ERα).
1.Adrenal androgens circulate to fat, muscle, and tumour
Source: www.accessdata.fda.gov/drugsatfda_docs/label/2014/020726s027lbl.pdf. Doses are for orientation; the current label governs.
Oral, self-administered, so it is a Part D drug: covered through a stand-alone Part D plan or Medicare Advantage drug benefit, usually on the specialty tier with 25 to 33% coinsurance until the annual cap ($2,000 in 2025, $2,100 in 2026). Letrozole, anastrozole and exemestane are all generic, low-tier Part D drugs.
Multi-source generic on low-cost tiers; usually no prior authorisation. Cash prices without insurance are modest.
Sources: Medicare.gov: Drug coverage (Part D) · Medicare.gov: Costs for Medicare drug coverage (annual out-of-pocket cap). Not medical or financial advice; verify with your plan.
Sources: NICE TA112 · SMC advice: letrozole and other aromatase inhibitors. Funding decisions are indication-specific and change monthly; verify with NICE and your treating team.
Letrozole approved for advanced breast cancer
Extended adjuvant treatment of early breast cancer in postmenopausal women who received 5 years of adjuvant tamoxifen
Accelerated approval on a surrogate endpoint, with a confirmatory trial required.
Postmenopausal women with HR positive early breast cancer
Letrozole adjuvant indication
Extended adjuvant treatment of early breast cancer in postmenopausal women who received 5 years of adjuvant tamoxifen
Confirmed: the accelerated approval of 2004 converted to traditional approval 5.5 years after it was granted.
Postmenopausal women with HR positive early breast cancer
Confirmed: the accelerated approval of 2005 converted to traditional approval 4.3 years after it was granted.
| Region | Year | Indication |
|---|---|---|
| US | 1997 | Advanced breast cancer after tamoxifen (letrozole) |
| US | 2005 | Adjuvant early breast cancer (letrozole) |
| Adverse event | Any grade | Grade 3+ |
|---|---|---|
| Arthralgia/myalgia | 35% | - |
| Hot flushes | 33% | - |
| Bone fracture (5-year) | 10% | - |
| Fatigue | 20% | - |
Events listed without rates were not read from a primary source; see the label. Blank cells mean the figure was not sourced, not that it is zero.
Read for the class this product belongs to (aromatase inhibitors) unless the answer names the product. Population figures from the cohorts named, not a prediction for one person. Blank where no source gives a recovery figure.
Check interactions for Letrozole (and other aromatase inhibitors) →
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Query for this drug: (TITLE:"Letrozole" OR ABSTRACT:"Letrozole" OR TITLE:"and other aromatase inhibitors" OR ABSTRACT:"and other aromatase inhibitors" OR TITLE:"Femara; anastrozole" OR ABSTRACT:"Femara; anastrozole" OR TITLE:"Arimidex ; exemestane" OR ABSTRACT:"Arimidex ; exemestane" OR TITLE:"Aromasin" OR ABSTRACT:"Aromasin") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Letrozole (and other aromatase inhibitors), not a curated reading list.
Shares HOBOE: A Phase 3 Study of Adjuvant Triptorelin and Tamoxifen, Letrozole, or Letrozole and Zoledronic Acid in Premenopausal Patients With Breast Cancer, Tubular carcinoma of the breast, Antiandrogens for hair: spironolactone, finasteride, dutasteride, COMET (Comparison of Operative versus Monitoring and Endocrine Therapy).
Shares Aromatase (CYP19A1), Antiandrogens for hair: spironolactone, finasteride, dutasteride, Aminoglutethimide, Acupuncture for aromatase-inhibitor joint pain.
Shares Study of GVV858 as a Single Agent or in Combination With Endocrine Therapy in Patients With HR+/HER2- Breast Cancer and Other Advanced Solid Tumors, PF-07104091 as a Single Agent and in Combination Therapy, Study to Test the Safety and Tolerability of PF-07220060 in Participants With Advance Solid Tumors, Study of AVZO-021 in Patients With Advanced Solid Tumors.
Shares PF-07104091 as a Single Agent and in Combination Therapy, Study of AVZO-021 in Patients With Advanced Solid Tumors, PALOMA-2, PATINA.
Shares MONARCH 3, Study of AVZO-021 in Patients With Advanced Solid Tumors, GLP-1 receptor agonists as adjuvant weight-loss therapy in HR-positive breast cancer, ER status (oestrogen receptor by IHC).
Shares Study of AVZO-021 in Patients With Advanced Solid Tumors, MONALEESA-2, ER status (oestrogen receptor by IHC), Invasive lobular carcinoma of the breast.
Shares Study to Test the Safety and Tolerability of PF-07220060 in Participants With Advance Solid Tumors, MONARCH 3, PALOMA-2, PATINA.
Shares Chemical carcinogenesis - receptor activation, ER status (oestrogen receptor by IHC), FES PET (oestrogen receptor imaging), Oestrogen receptor signalling.