The drug is appropriately used when using substantial amounts of aromatizing steroids, or when one is prone to gynecomastia and using moderate amounts of such steroids.  It is possible to reduce estrogen too much with Arimidex, and for this reason blood tests, or less preferably salivary tests, should be taken after the first week of use to determine if the dosing is correct. 
Three azole aromatase inhibitors are potent selective, it can inhibit the cytochrome P-450 dependent aromatase thereby blocking the biosynthesis of estrogen, but estrogen is the main factor that stimulates the growth of breast cancer cells. 
The treatment of breast cancer, especially for those with adjuvant hormone therapy after menopause after recurrence of women with advanced breast cancer.