FEMAMED 2.5 (Letrozole) belongs to a group of medicines called aromatase inhibitors. It is a hormonal (or “endocrine”) breast cancer treatment. Growth of breast cancer is frequently stimulated by estrogens which are female sex hormones. FEMAMED 2.5 reduces the amount of estrogen by blocking an enzyme (“aromatase”) involved in the production of estrogens and therefore may block the growth of breast cancer that needs estrogens to grow.