Hormones can be used to prevent breast cancer cells from multiplying. This type of treatment, called hormone therapy, is not the same as HRT, or hormone replacement therapy. There are many types of hormone treatments available. Your doctor can help you determine which is right for you. Side effects may include infertility, blood clots, stroke, and more. These should be discussed with your doctor. Follow the links below to find WebMD's comprehensive coverage about how hormone therapy works, what to expect, and much more.