Arimidex: Uses, Dosage & Side Effects
A potent aromatase inhibitor used to treat hormone receptor-positive breast cancer in postmenopausal women by dramatically reducing estrogen levels in the body
Arimidex (anastrozole) is a third-generation aromatase inhibitor used primarily for the treatment of hormone receptor-positive breast cancer in postmenopausal women. It works by blocking the aromatase enzyme, which is responsible for converting androgens into estrogen in peripheral tissues. By reducing circulating estrogen levels by approximately 80–85%, Arimidex effectively starves hormone-sensitive breast cancer cells of the estrogen they require for growth. It is available as a 1 mg film-coated tablet taken once daily. Arimidex is used both as adjuvant therapy following surgery for early breast cancer and as first-line treatment for advanced or metastatic disease. The landmark ATAC trial demonstrated that anastrozole provides superior disease-free survival compared to tamoxifen in postmenopausal women with early hormone receptor-positive breast cancer.
Quick Facts: Arimidex
Key Takeaways
- Arimidex (anastrozole) is a potent aromatase inhibitor that reduces estrogen levels by approximately 80–85%, making it highly effective against hormone receptor-positive breast cancer in postmenopausal women.
- It is taken as a single 1 mg tablet once daily, with or without food, and is typically prescribed for 5 years as adjuvant treatment following breast cancer surgery to reduce the risk of recurrence.
- The ATAC trial demonstrated that Arimidex provides superior disease-free survival and fewer serious side effects (including fewer blood clots and uterine cancers) compared to tamoxifen in postmenopausal women with early breast cancer.
- The most common side effects include hot flashes, joint pain and stiffness, and bone thinning (osteoporosis); regular bone density monitoring is recommended during treatment.
- Arimidex is not suitable for premenopausal women as a standalone therapy and must not be taken with tamoxifen or estrogen-containing medications, as these can reduce its effectiveness.
What Is Arimidex and What Is It Used For?
Arimidex contains the active substance anastrozole, a potent and highly selective non-steroidal aromatase inhibitor. Aromatase inhibitors represent one of the most important classes of medications in the treatment of hormone-sensitive breast cancer. They work by targeting the aromatase enzyme (also known as CYP19A1), a cytochrome P450 enzyme complex that catalyzes the final step in estrogen biosynthesis – the conversion of androgens (androstenedione and testosterone) into estrogens (estrone and estradiol) in peripheral tissues such as adipose tissue, muscle, liver, and within breast cancer cells themselves.
In postmenopausal women, the ovaries are no longer the primary source of estrogen. Instead, estrogen is produced through the aromatization of adrenal androgens in peripheral tissues. By inhibiting the aromatase enzyme, anastrozole reduces the circulating levels of estradiol by approximately 80% within 24 hours of administration and achieves a reduction of approximately 85% with continued daily dosing. This profound reduction in estrogen deprives hormone receptor-positive breast cancer cells of the hormonal stimulus they need for growth and proliferation, resulting in tumor regression or prevention of recurrence.
Anastrozole was first approved by the U.S. Food and Drug Administration (FDA) in 1995 for the treatment of advanced breast cancer and later received approval for adjuvant use in early breast cancer based on the results of the landmark Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial. It is approved by regulatory authorities worldwide, including the European Medicines Agency (EMA), and is listed on the World Health Organization (WHO) Model List of Essential Medicines, underscoring its critical role in breast cancer treatment globally.
Arimidex is indicated for the following uses:
- Adjuvant treatment of early hormone receptor-positive breast cancer: Arimidex is used in postmenopausal women following surgery (and potentially radiation and/or chemotherapy) to reduce the risk of breast cancer recurrence. The ATAC trial, involving over 9,000 postmenopausal women, demonstrated that 5 years of anastrozole provided superior disease-free survival compared to 5 years of tamoxifen, with a 13% reduction in the risk of recurrence. The benefit was particularly pronounced in patients with hormone receptor-positive tumors.
- Adjuvant treatment after 2–3 years of tamoxifen: In some treatment strategies, patients begin adjuvant endocrine therapy with tamoxifen and are then switched to anastrozole to complete 5 years of total endocrine therapy. This sequential approach has been shown to provide additional benefit in reducing recurrence rates compared to continuing tamoxifen for the full 5 years.
- First-line treatment of advanced or locally advanced breast cancer: Arimidex is used as initial treatment for hormone receptor-positive advanced or metastatic breast cancer in postmenopausal women. Clinical trials have shown anastrozole to be at least as effective as tamoxifen in this setting, with a more favorable side effect profile in certain respects.
- Treatment of advanced breast cancer after tamoxifen failure: Arimidex can be used as second-line therapy in postmenopausal women whose disease has progressed on tamoxifen or other anti-estrogen therapy.
Breast cancer is the most commonly diagnosed cancer in women worldwide, with approximately 2.3 million new cases diagnosed each year according to the World Health Organization. Roughly 70–80% of all breast cancers are hormone receptor-positive (ER+ and/or PR+), meaning they express estrogen receptors, progesterone receptors, or both on the surface of cancer cells. For these patients, endocrine therapy – including aromatase inhibitors like anastrozole – is a cornerstone of treatment that significantly improves survival outcomes.
Anastrozole belongs to the third generation of aromatase inhibitors, which are characterized by their high potency, selectivity, and favorable tolerability profiles compared to earlier agents. The three third-generation aromatase inhibitors – anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin) – are all recommended by major international guidelines (NCCN, ESMO, ASCO) as preferred adjuvant endocrine therapy for postmenopausal women with hormone receptor-positive early breast cancer.
What Should You Know Before Taking Arimidex?
Contraindications
Understanding the absolute contraindications for Arimidex is essential before starting treatment. The following situations represent circumstances in which this medication must not be used:
- Premenopausal women: Arimidex is not indicated for use in premenopausal women. In premenopausal women, the ovaries are the primary source of estrogen, and aromatase inhibition alone does not adequately suppress ovarian estrogen production. Using anastrozole in premenopausal women without concurrent ovarian function suppression would result in a compensatory increase in gonadotropin levels (LH and FSH), potentially stimulating increased ovarian estrogen production.
- Hypersensitivity: Do not take Arimidex if you are allergic to anastrozole or any of the excipients in the tablet formulation.
- Pregnancy and breastfeeding: Arimidex is contraindicated during pregnancy and lactation. Anastrozole may cause fetal harm based on its mechanism of action and findings from animal studies.
- Concurrent tamoxifen use: Arimidex should not be co-administered with tamoxifen. In the ATAC trial, the combination arm (anastrozole plus tamoxifen) showed no superior efficacy compared with tamoxifen alone, and tamoxifen reduced the plasma concentration of anastrozole by approximately 27%.
- Estrogen-containing therapies: Estrogen-containing medications, including hormone replacement therapy (HRT), would directly counteract the mechanism of action of anastrozole and must not be used concurrently.
Warnings and Precautions
Arimidex lowers estrogen levels, which may lead to a reduction in bone mineral density (BMD) over time, increasing the risk of osteoporosis and fractures. Bone density should be assessed at the start of treatment and monitored regularly throughout therapy. Patients with osteoporosis or at risk of osteoporosis should receive appropriate treatment (e.g., calcium, vitamin D supplementation, and potentially bisphosphonates) alongside Arimidex.
Before and during treatment with Arimidex, inform your doctor if any of the following apply to you:
- Osteoporosis or bone fragility: Because anastrozole significantly reduces estrogen levels, it decreases bone mineral density. In the ATAC trial, patients receiving anastrozole had a higher incidence of fractures (11%) compared to tamoxifen (7.7%) over 5 years. Baseline and periodic bone density assessments (DEXA scans) are recommended. Lifestyle measures such as weight-bearing exercise, adequate calcium intake (1000–1200 mg/day), and vitamin D supplementation (800–1000 IU/day) are important preventive strategies.
- Cardiovascular risk: While the ATAC trial showed a similar overall cardiovascular event rate between anastrozole and tamoxifen, patients should discuss their cardiovascular risk factors with their doctor. Reductions in estrogen may influence lipid profiles, and cholesterol levels should be monitored during treatment.
- Liver disease: Anastrozole is primarily metabolized by the liver. While no dose adjustment is required for mild hepatic impairment, the safety of anastrozole has not been established in patients with severe hepatic impairment. Liver function should be monitored, especially in patients with known liver conditions.
- Kidney disease: No dose adjustment is needed for patients with mild to moderate renal impairment (creatinine clearance >20 mL/min). Anastrozole has not been studied in patients with severe renal impairment, and caution is advised.
- Musculoskeletal symptoms: Joint pain (arthralgia), joint stiffness, and musculoskeletal disorders are among the most frequently reported side effects. These symptoms may be severe enough to warrant treatment discontinuation in some patients. Discuss management strategies with your doctor if joint symptoms significantly affect your quality of life.
- Allergic reactions: Cases of angioedema, urticaria, and anaphylaxis have been reported uncommonly. Seek immediate medical attention if you experience difficulty breathing, swelling of the face, lips, tongue, or throat, or severe skin reactions.
Pregnancy and Breastfeeding
Arimidex is contraindicated during pregnancy. Although the vast majority of patients prescribed anastrozole are postmenopausal, it is important to confirm menopausal status before initiating treatment. In premenopausal women receiving anastrozole in combination with ovarian suppression therapy, pregnancy must be excluded before starting treatment and effective non-hormonal contraception must be used throughout therapy and for at least 2 weeks after the last dose.
Animal reproductive studies have shown that anastrozole may cause fetal harm. There are no adequate and well-controlled studies in pregnant women. If pregnancy occurs during treatment, the patient should be informed of the potential risk to the fetus and the benefit–risk balance should be carefully evaluated.
It is not known whether anastrozole or its metabolites are excreted in human breast milk. Because of the potential for harm to the nursing infant, breastfeeding should be discontinued before starting Arimidex therapy.
Driving and Operating Machinery
Arimidex is unlikely to impair the ability to drive or operate machinery. However, weakness, somnolence (drowsiness), and asthenia (lack of energy) have been reported as occasional side effects. Patients who experience these symptoms should exercise caution when driving or operating heavy machinery until they know how the medication affects them.
How Does Arimidex Interact with Other Drugs?
Anastrozole has a relatively favorable drug interaction profile compared to many other oncology medications. In vitro studies have demonstrated that at clinically relevant concentrations, anastrozole does not inhibit CYP1A2, CYP2C8/9, CYP2D6, or CYP3A4. This means that significant pharmacokinetic interactions with drugs metabolized by these cytochrome P450 enzymes are generally not expected. However, there are important pharmacodynamic interactions that must be considered.
The metabolism of anastrozole itself involves N-dealkylation, hydroxylation, and glucuronidation. While CYP3A4 and aldehyde oxidase are involved in the metabolism of anastrozole to some degree, clinical studies with cimetidine (a known enzyme inhibitor) showed no clinically significant effect on the pharmacokinetics of anastrozole. Antipyrine studies also demonstrated that anastrozole does not significantly affect the clearance of drugs metabolized by mixed-function oxidases.
Major Interactions
| Interacting Drug | Effect | Clinical Significance |
|---|---|---|
| Tamoxifen | Reduces anastrozole plasma levels by approximately 27%; no additional efficacy benefit from combination | Do not co-administer – tamoxifen diminishes the effectiveness of anastrozole |
| Estrogen-containing therapies (HRT, oral contraceptives) | Directly counteracts the mechanism of action of anastrozole by providing exogenous estrogen | Contraindicated – completely negates the therapeutic effect |
| LHRH analogues (goserelin, leuprolide) | In premenopausal women, LHRH analogues suppress ovarian function, enabling the use of aromatase inhibitors | Combination used in premenopausal setting – monitor under specialist guidance |
Minor Interactions
| Drug/Category | Effect | Recommendation |
|---|---|---|
| Cimetidine | A known enzyme inhibitor; no clinically significant effect on anastrozole levels demonstrated in clinical studies | No dose adjustment required |
| Warfarin and other anticoagulants | No formal interaction studies; no clinically relevant interaction expected based on metabolic profile | Standard monitoring of INR recommended |
| Bisphosphonates (alendronate, zoledronic acid) | No pharmacokinetic interaction; often co-prescribed to protect bone density during aromatase inhibitor therapy | Beneficial combination – recommended for patients at risk of osteoporosis |
| CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib) | CDK4/6 inhibitors are commonly combined with aromatase inhibitors for advanced HR+ breast cancer; no pharmacokinetic interaction with anastrozole expected | Established combination in advanced breast cancer – follow oncologist guidance |
It is always important to tell your healthcare provider about all medications, vitamins, supplements, and herbal products you are taking. While anastrozole has a low risk of pharmacokinetic interactions, individual responses can vary, and your doctor should have a complete picture of your medication regimen to ensure safe and effective treatment.
What Is the Correct Dosage of Arimidex?
The dosing of anastrozole is straightforward compared to many other oncology medications. The same dose is used across all approved indications, making it easy for patients and healthcare providers to manage. Anastrozole should be taken at approximately the same time each day to maintain consistent blood levels.
Adults
Standard Adult Dosage
The recommended dose of Arimidex is 1 mg (one tablet) taken orally once daily. The tablet may be taken with or without food. There is no need to adjust the timing relative to meals, as food does not significantly affect the absorption of anastrozole.
| Indication | Dose | Duration |
|---|---|---|
| Adjuvant early breast cancer | 1 mg once daily | 5 years (or until recurrence) |
| Switch after 2–3 years tamoxifen | 1 mg once daily | Remainder of 5 years total endocrine therapy |
| Advanced/metastatic breast cancer | 1 mg once daily | Until disease progression or unacceptable toxicity |
In the adjuvant setting, the optimal duration of aromatase inhibitor therapy has been the subject of extensive research. The ATAC trial established 5 years as the standard duration. More recently, extended adjuvant trials have explored whether continuing aromatase inhibitor therapy beyond 5 years provides additional benefit. The MA.17R trial demonstrated a modest improvement in disease-free survival with extended letrozole therapy (another aromatase inhibitor) beyond 5 years, and this concept may apply to anastrozole as well. Your oncologist will advise on the optimal duration for your specific situation based on your individual risk profile.
Children
Pediatric Use
Arimidex is not recommended for use in children and adolescents. The safety and efficacy of anastrozole have not been established in pediatric patients. Clinical studies in children and adolescents (boys with short stature and delayed puberty, girls with McCune-Albright Syndrome and progressive precocious puberty) did not demonstrate sufficient efficacy, and anastrozole is not indicated for these populations.
Elderly
Elderly Patients
No dose adjustment is required in elderly patients. The pharmacokinetics of anastrozole are not significantly affected by age. Since breast cancer is more prevalent in older women, a substantial proportion of patients treated with Arimidex are over 65 years of age. The ATAC trial included patients up to 89 years old, and the safety and efficacy profile was consistent across age groups.
Missed Dose
If you miss a dose of Arimidex, take it as soon as you remember, unless it is close to the time of your next scheduled dose. In that case, skip the missed dose and take the next dose at the regular time. Do not take a double dose to make up for the missed one. Missing an occasional dose is unlikely to significantly affect treatment efficacy given the long elimination half-life of anastrozole (approximately 40–50 hours). However, try to take your medication consistently each day, as regular dosing is important for maintaining optimal estrogen suppression.
Overdose
Clinical experience with accidental overdose of anastrozole is limited. In clinical trials, single doses of up to 60 mg were administered to healthy male volunteers and single doses of up to 10 mg were given to postmenopausal women without clinically significant adverse events. There is no specific antidote for anastrozole overdose. Treatment should be symptomatic and supportive. If an overdose is suspected, contact your local poison control center or seek emergency medical attention. Given the long half-life of anastrozole, monitoring should continue for an appropriate period. Dialysis is unlikely to be useful in cases of overdose, as anastrozole is not highly protein-bound.
What Are the Side Effects of Arimidex?
Like all medications, Arimidex can cause side effects, although not everybody gets them. Many of the side effects associated with anastrozole are a direct consequence of its mechanism of action – the profound reduction in circulating estrogen levels. Understanding the frequency and nature of these side effects can help patients and healthcare providers manage them effectively and make informed treatment decisions.
The side effect profile of anastrozole has been extensively characterized in large clinical trials, most notably the ATAC trial involving over 6,000 patients randomized to anastrozole or tamoxifen. The following frequencies are based on combined data from clinical trials and post-marketing surveillance:
Very Common
Affects more than 1 in 10 patients (>10%)
- Hot flashes (hot flushes) – the most commonly reported side effect, affecting up to 36% of patients
- Joint pain and stiffness (arthralgia) – affects approximately 35% of patients; the most common reason for treatment discontinuation
- Nausea – usually mild and often improves with continued treatment
- Fatigue and weakness (asthenia) – general tiredness and reduced energy levels
- Headache
Common
Affects 1 to 10 in 100 patients (1–10%)
- Bone thinning (osteoporosis) and increased fracture risk
- Skin rash
- Diarrhea
- Vomiting
- Hair thinning (alopecia)
- Vaginal dryness
- Vaginal bleeding (particularly in the first few weeks after switching from other hormonal therapy)
- Elevated cholesterol levels (hypercholesterolemia)
- Loss of appetite (anorexia)
- Peripheral edema (swelling)
- Drowsiness (somnolence)
- Carpal tunnel syndrome
- Mood changes, including depression
- Musculoskeletal pain, bone pain, and muscle stiffness
Uncommon
Affects 1 to 10 in 1,000 patients (0.1–1%)
- Allergic reactions (hypersensitivity), including urticaria (hives)
- Angioedema (swelling of face, lips, tongue, or throat)
- Elevated liver enzymes (gamma-GT, bilirubin)
- Hepatitis (liver inflammation)
- Trigger finger (stenosing tenosynovitis)
- Increased blood levels of calcium (hypercalcemia) – with or without an increase in parathyroid hormone
Rare
Affects fewer than 1 in 1,000 patients (<0.1%)
- Erythema multiforme (a serious skin condition with target-like lesions)
- Stevens-Johnson syndrome (severe blistering skin reaction)
- Cutaneous vasculitis (inflammation of blood vessels in the skin), including reports of Henoch-Schönlein purpura
- Anaphylaxis (severe, life-threatening allergic reaction)
- Severe hepatic dysfunction (in patients with pre-existing liver disease)
Joint pain (arthralgia) is the most common reason patients discontinue aromatase inhibitor therapy. Strategies to manage this side effect include regular physical exercise (especially stretching and low-impact activities like swimming, walking, and yoga), maintaining a healthy weight, using over-the-counter analgesics such as paracetamol or NSAIDs as recommended by your doctor, vitamin D supplementation, and acupuncture, which has shown some benefit in clinical studies. If joint symptoms are severe and intolerable, your oncologist may consider switching to a different aromatase inhibitor (letrozole or exemestane), as some patients tolerate one agent better than another.
Compared to tamoxifen in the ATAC trial, anastrozole was associated with fewer thromboembolic events (blood clots), fewer cases of endometrial cancer (cancer of the uterine lining), and less vaginal bleeding and vaginal discharge. However, anastrozole was associated with more musculoskeletal complaints, more fractures, and more joint stiffness. The choice between aromatase inhibitors and tamoxifen involves weighing these different risk profiles against each other in the context of each patient’s individual health status and preferences.
If you experience any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed above. You can also report side effects directly to your national medicines regulatory authority.
How Should You Store Arimidex?
Proper storage of medications is essential to maintain their effectiveness and safety throughout the treatment period. Arimidex tablets should be stored under the following conditions:
- Temperature: Store at room temperature, below 30°C (86°F). Do not refrigerate or freeze the tablets.
- Light and moisture: Keep the tablets in their original packaging (blister pack or bottle) to protect them from light and moisture. Do not transfer tablets to other containers unless specifically designed for medication storage.
- Children: Keep Arimidex out of the sight and reach of children. Store in a secure location.
- Expiry date: Do not use Arimidex after the expiry date stated on the carton and blister packaging. The expiry date refers to the last day of that month.
- Disposal: Do not dispose of medications via wastewater or household waste. Ask your pharmacist about how to properly dispose of medicines no longer required. This helps protect the environment.
If you notice any changes in the appearance of your tablets (such as discoloration, crumbling, or an unusual odor), do not take them and consult your pharmacist. Tablets that appear damaged or deteriorated may have compromised stability and should be replaced.
What Does Arimidex Contain?
Understanding the complete composition of your medication is important, particularly if you have known allergies or intolerances to specific ingredients. Each Arimidex 1 mg film-coated tablet contains:
Active Ingredient
- Anastrozole 1 mg – the pharmacologically active component responsible for aromatase inhibition
Inactive Ingredients (Excipients)
The tablet core contains:
- Lactose monohydrate: A commonly used tablet filler. Patients with rare hereditary problems of galactose intolerance, total lactase deficiency, or glucose-galactose malabsorption should not take this medicine.
- Povidone (K30): A binding agent that helps hold the tablet together.
- Sodium starch glycolate: A disintegrant that helps the tablet break apart in the gastrointestinal tract for absorption. Each tablet contains less than 1 mmol sodium (23 mg), meaning it is essentially sodium-free.
- Magnesium stearate: A lubricant used during the tablet manufacturing process.
The film coating contains:
- Hypromellose (hydroxypropyl methylcellulose): Forms the coating film.
- Macrogol 300: A plasticizer for the coating.
- Titanium dioxide (E171): Provides the white color of the tablet and protects the contents from light.
Arimidex tablets are white, round, biconvex film-coated tablets. They are marked with the Arimidex logo on one side and “Adx1” on the other side. They are available in calendar blister packs of 28 tablets (corresponding to 4 weeks of treatment) and bottles of 30 tablets.
Frequently Asked Questions About Arimidex
Arimidex (anastrozole) is an aromatase inhibitor used to treat hormone receptor-positive breast cancer in postmenopausal women. It is used both as adjuvant therapy after surgery to reduce the risk of cancer recurrence and as first-line treatment for advanced or metastatic breast cancer. Arimidex works by blocking the aromatase enzyme, which dramatically reduces estrogen levels and deprives cancer cells of the hormone they need to grow.
For adjuvant treatment of early breast cancer, Arimidex is typically taken for 5 years. Some patients may be switched to Arimidex after 2–3 years of tamoxifen for a total of 5 years of endocrine therapy. Extended adjuvant therapy beyond 5 years may be considered for some high-risk patients. For advanced or metastatic breast cancer, treatment continues for as long as the cancer responds and the drug is tolerated.
Arimidex should not be used in premenopausal women as a standalone treatment for breast cancer. In premenopausal women, the ovaries are the primary source of estrogen, and aromatase inhibition alone cannot adequately suppress this ovarian production. However, in certain clinical settings, premenopausal women may receive Arimidex in combination with ovarian suppression therapy (such as LHRH agonists like goserelin), which effectively shuts down ovarian function and allows the aromatase inhibitor to work effectively.
The most common side effects include hot flashes (affecting up to 36% of patients), joint pain and stiffness (approximately 35%), nausea, fatigue, and headache. Bone thinning (osteoporosis) and increased fracture risk are also important concerns. Joint pain is the most frequent reason for treatment discontinuation. Most side effects are manageable with appropriate interventions and tend to improve over time.
Weight gain is not among the most common side effects of Arimidex, but some patients do report changes in body weight. In the ATAC trial, weight gain was slightly less common with anastrozole compared to tamoxifen. Maintaining a healthy weight is important for breast cancer outcomes. If you notice significant weight changes during treatment, discuss this with your doctor and consider dietary counseling and exercise as part of your overall cancer care plan.
Arimidex (anastrozole) and tamoxifen both treat hormone receptor-positive breast cancer but work differently. Arimidex blocks estrogen production by inhibiting the aromatase enzyme, while tamoxifen blocks estrogen from binding to cancer cell receptors. Arimidex is only for postmenopausal women, whereas tamoxifen works in both pre- and postmenopausal women. The ATAC trial showed Arimidex provided better disease-free survival with fewer blood clots and uterine cancers than tamoxifen, but with more joint pain and fractures. Your oncologist will recommend the best option based on your individual situation.
References
- European Medicines Agency (EMA). Arimidex (anastrozole) – Summary of Product Characteristics. Last updated 2025. Available from: www.ema.europa.eu
- U.S. Food and Drug Administration (FDA). Arimidex (anastrozole) tablets – Prescribing Information. Revised 2024. Available from: www.accessdata.fda.gov
- The ATAC Trialists’ Group. Results of the ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial after completion of 5 years’ adjuvant treatment for breast cancer. The Lancet. 2005;365(9453):60–62. doi:10.1016/S0140-6736(04)17666-6
- Cuzick J, Sestak I, Baum M, et al. Effect of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: 10-year analysis of the ATAC trial. The Lancet Oncology. 2010;11(12):1135–1141. doi:10.1016/S1470-2045(10)70257-6
- National Comprehensive Cancer Network (NCCN). Clinical Practice Guidelines in Oncology: Breast Cancer. Version 2.2025. Available from: www.nccn.org
- Cardoso F, Kyriakides S, Ohno S, et al. Early breast cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology. 2019;30(8):1194–1220. doi:10.1093/annonc/mdz173
- Burstein HJ, Lacchetti C, Anderson H, et al. Adjuvant Endocrine Therapy for Women With Hormone Receptor–Positive Breast Cancer: ASCO Clinical Practice Guideline Focused Update. Journal of Clinical Oncology. 2019;37(5):423–438. doi:10.1200/JCO.18.01160
- World Health Organization (WHO). Model List of Essential Medicines – 23rd List, 2023. Geneva: WHO; 2023.
- British National Formulary (BNF). Anastrozole monograph. Available from: bnf.nice.org.uk
- Crew KD, Greenlee H, Capodice J, et al. Prevalence of joint symptoms in postmenopausal women taking aromatase inhibitors for early-stage breast cancer. Journal of Clinical Oncology. 2007;25(25):3877–3883. doi:10.1200/JCO.2007.10.7573
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