Hormone therapy for breast cancer is a treatment for breast cancers that are sensitive to hormones. The most common forms of hormone therapy for breast cancer work by blocking hormones from attaching to cancer cells or by decreasing your body's production of hormones.Hormone therapy for breast cancer is often used after surgery to reduce the risk that the cancer will return. Hormone therapy for breast cancer may also be used to shrink a tumor before an operation, making it more likely the cancer will be removed completely.If your cancer has spread to other parts of your body, hormone therapy for breast cancer may help control it.