Exemestane, is a steroidal aromatase inhibitor medication primarily used to treat hormone receptor-positive breast cancer in postmenopausal women. It works by irreversibly binding to the aromatase enzyme, which blocks the conversion of androgens to estrogens in peripheral tissues, thereby significantly lowering circulating estrogen levels to slow or halt the growth of estrogen-dependent tumors. Often prescribed after 2-3 years of tamoxifen therapy to complete a 5-year adjuvant treatment course, it is also used for advanced breast cancer that progresses post-tamoxifen.