Topic #2: Chemotherapy with Multiple Drugs Instead of with One Drug for Breast Cancer that Has Spread


Metastatic breast cancer is when the disease has spread beyond the breast and lymph nodes near the breast to other parts of the body. Treatment options for people with metastatic breast cancer often include chemotherapy. Chemotherapy is the use of drugs to kill cancer cells, usually by stopping the cancer cells’ ability to grow and spread. Chemotherapy can be given one drug at a time or in combinations of drugs at the same time. Certain types of targeted therapy called monoclonal antibodies, which can include trastuzumab (Herceptin) and pertuzumab (Perjeta), are often used with chemotherapy.

Chemotherapy with a combination of drugs may slow the growth of metastatic breast cancer slightly longer than chemotherapy with one drug. However, the use of more than one drug at a time has not been shown to lengthen patients’ lives. In addition, patients who receive a combination of drugs experience side effects more often and more severely than those who receive a single drug at a time. Increases in side effects often worsen a patient’s quality of life and lead to decreases in the chemotherapy dose to avoid or reduce the side effects.


In general, ASCO recommends that people with metastatic breast cancer receive one effective drug at a time because this is less likely to cause severe side effects, may improve a patient’s quality of life, and usually does not impact survival. However, combinations of drugs for chemotherapy may be useful and worth the risk of side effects when the amount of cancer needs to be reduced quickly because it is causing severe symptoms itself or the patient’s life is in immediate danger.

What this means for patients

A diagnosis of metastatic breast cancer is very stressful. Treatment for metastatic breast cancer is a balance between slowing the growth of the cancer and maintaining a patient’s quality of life, by avoiding too many or too severe side effects. In addition to treatment to slow the cancer growth, such as chemotherapy, patients should receive supportive or palliative care to help manage side effects.

If you have metastatic breast cancer, it is important to talk with doctors who are experienced in treating this stage of cancer, because there can be different opinions about the best treatment plan. You may also want to consider seeking a second opinion before starting treatment, so you are comfortable with the treatment plan chosen.

Questions to ask your doctor

  • What stage of breast cancer do I have? What does this mean?
  • What are my treatment options?
  • Will I receive chemotherapy? Will it include one drug or a combination of different drugs?
  • Are there other treatment options, such as hormone therapy or radiation therapy?
  • What are the side effects of each of these treatment options?
  • How can the side effects be managed?

For More Information

Guide to Breast Cancer

Caring for the Symptoms of Cancer and its Treatment

Managing Side Effects