Surgery and radiation therapy are only effective against local disease -- tumors that are found in or close to the breast. But cancer cells from the original tumor will sometimes spread to other parts of the body. So systemic treatment -- treatment that targets cancer cells throughout the body -- may be needed. Systemic treatment may be chemotherapy, which uses drugs to kill cancer cells, or it may be hormonal or biological therapies, which use drugs that block the action and growth of cancer cells by means other than directly killing the cells. (Hormonal and biological therapy drugs are discussed in the next section.) These therapies have been shown to lower the chances that a recurrence will occur.
Systemic treatment is routinely suggested for women who have evidence of disease in the lymph nodes or locally advanced disease and some doctors recommend systemic therapy for any woman whose original tumor was larger than 1 cm in diameter, regardless of the lymph node status. This is because undetectable cancer cells may have spread to other organs. These micrometastases, as they are called, have not yet formed tumors large enough to be seen on a CT scan or felt on examination. Yet, if left untreated they will grow into larger tumors. Systemic treatment is intended to prevent that from happening and to prevent a recurrence of the disease in the future.
Chemotherapy is usually scheduled for after surgery and before radiation therapy. This kind of chemotherapy is called "adjuvant chemotherapy." Occasionally "neoadjuvant" therapy is given before surgery, to reduce the size of a tumor and make it easier for the surgeon to perform the surgery. It is prescribed by a medical oncologist and may be given as an intravenous injection or in pill form, depending on the medication. In some cases, a port or catheter is placed under the skin of your chest during a short procedure if your veins are not adequate for therapy. It remains in place until all your chemotherapy is complete. If your doctor thinks you should have one of these, the procedure will be explained in detail.
Chemotherapy drugs act by interrupting the cell's growth and replication cycle in some way. In treating breast cancer, doctors often use a combination of two or three drugs at one time. The different drugs all act on a different part of the cell's reproductive cycle, so by using more than one you are increasing the likelihood that all cancer cells will be affected, including those that might prove resistant to one drug or another.
The choice of drugs depends on several factors, including the prognostic factors that appear in your pathology report, your age, and your menopausal status. A typical course of chemotherapy might last three to six months, with therapy being given every two to three weeks or so. Usually, you spend a few hours or the day in the treatment center for each treatment; it rarely requires an overnight stay. It is generally a good idea to ask your doctor to tell you the dose for each drug you are on. While millions of doses of chemotherapy are safely given around the country every day, you could prevent the minuscule chance of an error by knowing your dosage and confirming it before the drug or drugs are given.
Drugs are given singly or in combinations to treat breast cancer. Combinations are often identified by the first letters of the drugs used. For example, CMF stands for cyclophosphamide (Cytoxan®), methotrexate, and fluorouracil. Your doctor will describe the drug or drug combinations he or she will prescribe for you. Many of the drugs used in the treatment of breast cancer are listed below. We've listed both the trade name and the generic name of each drug. Click on the drug to get more detailed information on how it is given and the side effects it can cause. You may also be on new drugs that are part of clinical trials. These are not listed here, but are well described on the informed consent document you will sign before beginning the trial.
The drugs may also affect noncancerous cells to some degree. The interval between treatments is designed to give these cells a chance to recover. Unfortunately, it is the effect on healthy cells that causes the side effects of chemotherapy. Possible side effects are hair loss, mouth sores, diarrhea, nausea and vomiting, fatigue, weight gain, low blood counts (leaving you vulnerable to infection), easy bruising, and bleeding gums. Not everyone experiences side effects and many of these problems can be treated, so report any side effects to your doctor. (See also Coping with Side Effects.) If you develop fevers, shaking, chills, bleeding, severe diarrhea, severe vomiting, or signs of dehydration, call your doctor immediately.
Some chemotherapy can also cause reproductive problems. About 1 / 3 of all women under the age of 40 who have chemotherapy will go into permanent menopause. Of those over 40, 2 / 3rds between 40 and 45, and 90 percent of those 46 and over will begin menopause. Some women will experience temporary or permanent infertility or menstrual irregularities. (See Menstrual Irregularities under Coping with Side effects for suggestions on dealing with problems related to menopause.) It is imperative that you use barrier contraception to avoid becoming pregnant during chemotherapy or hormonal therapy treatments.
Embryo Preservation
Some women in their childbearing years may want to consider embryo preservation before beginning chemotherapy treatment. The decision to preserve an embryo should only be made after a discussion with the medical oncologist. Unfortunately, there is very little available information on the safety or effectiveness of this intervention for women with breast cancer. However, in general, women are advised not to become pregnant for several years after treatment for breast cancer, because of uncertainties regarding the impact of high hormone levels as well as concerns that a pregnancy might be complicated by a recurrence of disease. Some of these same concerns could apply to the hormone levels needed to create the right uterine environment for embryo implantation. An additional concern is the delay in systemic treatment for breast cancer required to pursue embryo preservation. This could effect outcomes. The same reasoning would apply to creating the right uterine environment for embryo implantation.
Currently, only embryos can be frozen and thawed without damage. Both egg preservation and the preservation of an entire ovary are being studied, but the technology is not yet reliable.
High-Dose Chemotherapy
High-dose chemotherapy is a complex medical procedure that is used to treat some women with advanced breast cancer. It uses very high doses of chemotherapy given over a short period of time. Because these doses are so high, they can damage the blood-producing stem cells, which are found in the bone marrow. Thus, the patient requires an infusion or transplant of bone marrow or stem cells to restore normal functioning. The bone marrow or stem cells are collected from the patient before the high-dose chemotherapy begins and returned after chemotherapy is finished.
Studies are continuing to investigate whether there is any role for high dose therapy in the treatment of breast cancer. However, to date, there are no studies that definitively show an increased survival compared to standard dose therapy.
