Goal of Hormone Therapy for Breast Cancer

Hormones control the growth and activity of normal, healthy cells. Certain hormones, such as estrogen, can also fuel the growth of some tumors, including breast cancer. About two-thirds of breast cancers are sensitive to estrogen. This means that estrogen’s presence causes the tumor to grow.

Here’s how estrogen promotes tumor growth. It binds to a protein called an estrogen receptor, which is found in some breast cancer cells. When estrogen binds to this receptor, the cancer cells divide and the tumor grows.

Hormone therapy is also called endocrine therapy. It works by keeping cancer cells from getting the hormones they need to grow. It’s a systemic treatment, meaning that it can affect cancer cells all through the body. One way to think of hormone therapy is that it starves the tumor of the estrogen it needs to grow. The goal is to shrink the tumor and prevent it from coming back.

Research has shown that hormone therapy can extend your life if you have cancer cells that depend on hormones to grow. A doctor can decide if you will benefit from hormone therapy by doing a hormone receptor test on your breast tumor. This test tells the doctor if your cancer is using hormones to grow. Hormone therapy has little effect on cancers that aren’t hormone-dependent, so it is not used unless the tumor tests positive.