When a tumor is large, identified as aggressive, and/or involves the lymph nodes, some form of systemic adjuvant treatment, such as chemotherapy, is often recommended. This is usually administered postoperatively following surgery to destroy cancer cells that may have escaped into the lymph and blood vessels, thereby reducing the likelihood of a recurrence. On the other hand, a small tumor can shed cancer cells outside the breast.

Studies have shown that a combination of chemotherapy drugs is more effective than a single agent. The combination that has been favored for many years is CMF (cyclophosphamide [Cytoxan], methotrexate, and fluorouracil [5-FU]). Alternating CMF with a therapy that is Adriamycin-based, call CAF (cyclophosphamide [Cytoxan], Doxorubicin (Adriamycin), and flurorouracial [5-FU]), is becoming more common, as research demonstrate improved response rates. There are several other variations that include vincristine (Oncovin) and prednisone. Women who enter clinical trials may be offered new drugs and/or different combinations of widely used ones.

The decision of when to begin chemotherapy and how long treatment should last is very individualized and may vary from one doctor to another. Some combinations may be given in cycles lasting only two to six months; others are given for a year or more.

Investigators are looking at whether giving chemotherapy before surgery can shrink a larger tumor enough not only to permit a lumpectomy instead of a mastectomy but also to destroy cancer cells that have spread to other areas.

To learn more about chemotherapy, see the Cancer Treatment module.