Chemotherapy is a form of systemic treatment of invasive breast cancer. It is a cancer treatment that uses drugs to destroy cancer cells, stopping them from multiplying at points in the cells’ life cycle. These anti–cancer drugs work by killing cancer cells that may be in different parts of your body. Unfortunately, chemotherapy may also affect your healthy cells which is the cause of side effects. Since some anti–cancer drugs work more effectively together than alone, chemotherapy may consist of more than one drug. This is called combination therapy.

Sometimes chemotherapy is the only therapy a patient receives. More often, however, chemotherapy is used in addition to surgery and/or radiation therapy. When it is used for this purpose, it is called adjuvant therapy.

There are several reasons why chemotherapy may be given in addition to other treatment methods. For instance, chemotherapy may be used to shrink a tumor before surgery or radiation therapy. It also may be used after surgery and/or radiation therapy to help destroy any cancer cells that may remain.