Yes and no. Unfortunately, eBay has become something of a customer service nightmare for most people, as is evidenced by the results of any search for contact eBay, call eBay, chat with eBay, or similar phrases. Articles, blog posts, and websites offering contact information all give different answers, and most of them are wrong.
It inhibits the action of aromatase enzymes, which causes the body to produce less estrogen. Because many breast cancers are sensitive to estrogen, less estrogen in the body can help keep the cancer from spreading. Anastrozole is used for off-label reasons as well, such as treating excess estrogen production in men.
The difference between Letrozole and the other two major aromatase inhibitors is the fact that although it is utilized for the treatment of post-menopausal female breast cancer patients, it is actually specifically utilized for what is known as Estrogen receptor unknown breast cancer.