From the Guidelines
Anastrozole is a first-line hormonal therapy for postmenopausal women with hormone receptor-positive breast cancer, effective in reducing the risk of cancer recurrence and improving disease-free survival compared to older treatments like tamoxifen. It belongs to a class of medications called aromatase inhibitors that work by blocking the enzyme aromatase, which converts androgens into estrogens in postmenopausal women. By reducing estrogen production, anastrozole helps prevent estrogen-dependent breast cancer cells from growing and dividing. The standard dosage is 1 mg taken orally once daily, typically for 5-10 years as adjuvant therapy following surgery, radiation, or chemotherapy.
Key Points:
- Anastrozole may also be used as neoadjuvant therapy before surgery to shrink tumors, or as treatment for metastatic disease.
- Common side effects include joint pain, hot flashes, fatigue, and bone loss that may lead to osteoporosis.
- Regular bone density monitoring is recommended during treatment, and calcium and vitamin D supplements are often prescribed concurrently.
- Blood tests to monitor liver function are also typically performed periodically.
- Anastrozole should not be used in premenopausal women as it is ineffective in this population due to their different estrogen production mechanisms, as supported by studies such as 1.
Treatment Considerations:
- The choice between anastrozole and other aromatase inhibitors, such as letrozole or exemestane, should be based on individual patient factors and side effect profiles, as noted in 1.
- The optimal duration of anastrozole treatment is not established, but it is typically used for 5-10 years, as discussed in 1.
- Anastrozole has been shown to be effective in reducing the risk of breast cancer recurrence and improving disease-free survival in postmenopausal women with hormone receptor-positive breast cancer, as demonstrated in studies such as 1.
From the FDA Drug Label
Anastrozole tablets are indicated for adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer. Anastrozole tablets are indicated for the first-line treatment of postmenopausal women with hormone receptor-positive or hormone receptor unknown locally advanced or metastatic breast cancer. Anastrozole tablets are indicated for the treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy.
The role of Anastrozole (Astrazole) in the treatment of hormone receptor-positive breast cancer in postmenopausal women is to:
- Reduce estrogen production in the body, which can help slow or stop the growth of hormone receptor-positive breast cancer
- Be used as adjuvant treatment for early breast cancer
- Be used as first-line treatment for locally advanced or metastatic breast cancer
- Be used as second-line treatment for advanced breast cancer in women who have already been treated with tamoxifen 2
Key points:
- Anastrozole is a selective non-steroidal aromatase inhibitor that lowers serum estradiol concentrations 2
- Anastrozole is not indicated for use in premenopausal women 2, 2, 2
From the Research
Role of Anastrozole in Hormone Receptor-Positive Breast Cancer
- Anastrozole is a nonsteroidal aromatase inhibitor used in the treatment of hormone receptor-positive breast cancer in postmenopausal women 3, 4, 5.
- It works by reducing plasma estrogen levels, which can help slow the growth of breast cancer cells 3.
- Anastrozole has been shown to be effective in reducing breast cancer recurrence and improving overall survival in postmenopausal women with early-stage breast cancer 4, 6.
Efficacy of Anastrozole Compared to Tamoxifen
- Studies have compared the efficacy of anastrozole to tamoxifen in postmenopausal women with hormone receptor-positive breast cancer 4, 6.
- Anastrozole has been shown to be more effective than tamoxifen in reducing breast cancer recurrence and improving overall survival in some studies 4, 6.
- However, other studies have found similar efficacy between anastrozole and tamoxifen 3.
Safety and Tolerability of Anastrozole
- Anastrozole is generally well tolerated, with common adverse events including gastrointestinal disturbances, headache, and hot flushes 3, 4, 5.
- Anastrozole has been associated with an increased risk of bone fractures, particularly during the treatment period 4.
- However, anastrozole has been shown to have a lower incidence of thromboembolic events and vaginal bleeding compared to tamoxifen 6.
Clinical Use of Anastrozole
- Anastrozole is approved for use as an adjuvant treatment in postmenopausal women with early-stage, hormone receptor-positive breast cancer 4.
- It is also approved for use as a first-line treatment for advanced breast cancer in postmenopausal women 3, 6.
- Anastrozole may be considered as a treatment option for postmenopausal women with hormone receptor-positive breast cancer, particularly those who are at high risk of recurrence or have had a poor response to tamoxifen 4, 7.