Letromara belongs to the class of anti-estrogens. It works lowering estrogen levels in postmenopausal women to prevent certain types of breast cancer. Basically the Letrozole is a drug that was developed to address against breast cancer by inhibiting the aromatization. It is usually used as part of an aggressive treatment in post-menopausal women, to fight and reverse the spread of breast cancer after other treatments have failed (such as tamoxifen). This is probably the most efficient product on the market for this purpose currently, it is very similar to the structure and the action of his predecessor arimidex.