General Information

Anastrozole is a nonsteroidal aromatase inhibitor. Anastrozole is highly potent and specific for aromatase, and represents the fourth generation of aromatase inhibitors. Anastrozole significantly suppresses serum estradiol levels, and it offers an alternative to tamoxifen in postmenopausal women with breast cancer. Unlike aminoglutethimide, an early aromatase inhibitor, anastrozole does not inhibit adrenal steroid synthesis. Patients taking anastrozole, therefore, do not require glucocorticoid or mineralocorticoid replacement therapy. Anastrozole causes less weight gain than megestrol and may offer a survival advantage over megestrol in women with advanced breast cancer. Aromatase inhibitors are considered to be a standard of therapy and drug class of choice for the treatment of early breast cancer in postmenopausal women with hormone-receptor positive disease. The American Society of Clinical Oncology recommends that all postmenopausal women with hormone receptor-positive early breast cancer receive adjuvant aromatase inhibitor therapy. Options include 5 years of an aromatase inhibitor or sequential therapy with 2—3 years or 5 years of tamoxifen followed by 2—3 years or 5 years of an aromatase inhibitor.(1) Long-term data indicate that the improvements in disease-free survival persist for the 5 years during treatment and after drug discontinuation (see Dosage)(2)(3). Although not FDA-approved, several studies have shown that anastrozole further improves disease-free survival when used sequentially after 2—3 years of tamoxifen when compared to patients taking tamoxifen for 5 years.(4)5). Anastrozole was initially FDA-approved for the treatment of advanced breast cancer in postmenopausal women whose disease has progressed during tamoxifen therapy in December 1995. In September 2000, the FDA approved anastrozole for the first-line treatment of postmenopausal women with advanced or metastatic breast cancer. Approval for the adjuvant treatment of early breast cancer in postmenopausal women with hormone receptor positive disease was received in September 2002.