Femara (letrozole) is prescribed for the adjuvant (following surgery) treatment of postmenopausal women with hormone receptor-positive early stage breast cancer. You may see the positive result within 24 months of treatment. It is prescribed for treatment of early stage and advanced breast cancer in postmenopausal females and in women with estrogen receptor-positive or estrogen receptor-unknown breast cancer that has spread to another part of the body (metastatic cancer).