Letrozole is utilized treat early bosom malignant growth in ladies who have encountered menopause (change of life; end of month to month feminine periods) and who have had different therapies, for example, radiation or medical procedure to eliminate the cancer. It is likewise used to treat early bosom malignant growth in ladies who have encountered menopause and who have previously been treated with a drug called tamoxifen (Nolvadex) for a very long time. Letrozole is likewise utilized in ladies who have encountered menopause as a first therapy of bosom disease that has spread inside the bosom or to different region of the body or in ladies whose bosom malignant growth has deteriorated while they were taking tamoxifen. Letrozole is in a class of prescriptions called nonsteroidal aromatase inhibitors. It works by diminishing how much estrogen delivered by the body. This can slow or stop the development of certain kinds of bosom disease cells that need estrogen to develop.