Why it's done

Hormone therapy for breast cancer is only used to treat cancers that are hormone sensitive (hormone receptor positive breast cancers).

Doctors refer to these cancers as estrogen receptor positive (ER positive) or progesterone receptor positive (PR positive). This means that these breast cancers are fueled by the natural hormones estrogen or progesterone.

A doctor who specializes in analyzing blood and body tissue (pathologist) determines if your cancer is ER positive or PR positive by analyzing a sample of your cancer cells to see if they have receptors for estrogen or progesterone.

Hormone therapy for breast cancer can help to:

• Prevent cancer from coming back
• Decrease the risk of cancer developing in other breast tissue
• Slow or stop the growth of cancer that has spread
• Reduce the size of a tumor prior to surgery