Estrogen and progesterone are natural hormones produced in the body. Some breast cancer cells use these hormones to grow.

When these hormones attach to special proteins called hormone receptors, they can fuel cancer growth.

All breast cancers are tested to see if they have hormone receptors. If they do, they’re called hormone receptor-positive and can be treated with hormone therapy.

Hormone therapies slow or stop the growth of hormone receptor-positive tumors by preventing cancer cells from getting the hormones they need to grow.

For women, the drug options depend on whether or not they have gone through menopause. Men with hormone receptor-positive breast cancer most often take tamoxifen.

For early and locally advanced breast cancers that are hormone receptor-positive, treatment with the hormone therapies tamoxifen and/or an aromatase inhibitor lowers the risk of a breast cancer recurrence, reduces the chance of breast cancer in the opposite breast and improves survival.

Hormone receptor-positive breast cancers that are at high risk of recurrence are treated with hormone therapy combined with a CDK4/6 inhibitor which further slows cancer growth.

For more information, visit the Hormone Therapy page within the Treatment section of komen.org.