What is the first-line treatment for breast cancer in a postmenopausal woman?

The first-line treatment for breast cancer in a postmenopausal woman is an aromatase inhibitor, such as anastrozole. Aromatase inhibitors are particularly effective in postmenopausal women because they work by inhibiting the aromatase enzyme, which is responsible for converting androgens to estrogens in tissues. After menopause, the ovaries cease estrogen production, and most of the estrogen in the body comes from peripheral conversion of androgens. By reducing estrogen levels, aromatase inhibitors help slow or stop the growth of estrogen-sensitive tumors.

Tamoxifen, while a widely used treatment in premenopausal women and also in some postmenopausal women, is primarily a selective estrogen receptor modulator (SERM) rather than an aromatase inhibitor. It acts by blocking estrogen receptors but does not lower estrogen levels in the body. Given the hormonal environment in postmenopausal women, the aromatase inhibitors have demonstrated superior efficacy compared to tamoxifen in this population.

Chemotherapy, including anthracyclines, is usually reserved for specific situations such as high-risk early-stage breast cancer or metastatic disease, rather than as a primary treatment for hormone receptor-positive breast cancer in postmenopausal