Treating Breast Cancer: Adjuvant Therapy

Woman talking to healthcare provider.

If you have breast cancer, you will have many treatment choices. Before you decide which is best for you, weigh all of your choices. Be sure to discuss them with your healthcare providers and your loved ones. Your choices may include one or more types of adjuvant therapy. These are treatments used after breast surgery.

Radiation therapy

This treatment uses high-energy X-rays to kill cancer cells. Most often, it is used to kill cancer cells that may remain in your breast after surgery. Radiation also helps keep breast cancer from coming back. You’ll likely have this treatment if you had a lumpectomy (breast-conserving surgery). 


This treatment uses medicines that attack cancer cells. Chemotherapy can be given before or after surgery. Or it may be given on its own. It’s also used to help keep breast cancer from coming back. Your healthcare provider will decide if chemotherapy is right for you. Factors include the size of your tumor and where it has spread.

Hormone therapy

Hormone therapy is used when cancer cells respond to estrogen and progesterone. These two hormones are normally made by the body. With some types of breast cancer, the hormones bind to special sites called receptors on the cancer cells. This causes them to grow. To treat these types of tumors, two kinds of medicines may be used:

  • Selective estrogen receptor modulators (SERMs). These bind to hormone receptor-positive cancer cells and stop the cells from dividing.

  • Aromatase inhibitors. These reduce your body’s production of estrogen. With less estrogen to bind with, hormone receptor-positive cancer cells are less likely to grow.

Hormone therapy is commonly used after surgery to help keep hormone-receptive breast cancer from coming back. It is the usual first-line treatment for people with hormone-receptive breast cancer that has spread to other parts of the body. 

Targeted therapy

Specific kinds of targeted medicines for breast cancer include monoclonal antibodies and tyrosine kinase inhibitors. These medicines work by stopping or slowing the growth of some breast cancers by blocking certain proteins in or on the cancer cells. For breast cancer, the protein is most often a growth factor protein called HER-2. Breast cancers that have a lot of the HER-2 protein are called HER-2 positive. Breast cancer cells are tested for HER-2 in the lab. Your healthcare provider may suggest targeted therapy if your breast cancer is HER-2 positive.