Broadly speaking, chemotherapy is the use of anti-cancer drugs to slow and halt the growth of rapidly dividing cancerous cells in your body.

Effective Medicine

Get an overview of chemotherapy in Your Guide to Cancer Care.

Learn about:

How chemotherapy is used

Breast cancer chemotherapy is typically administered intravenously — through a vein — or orally in the form of pills. It’s used to treat breast cancer in three main ways:

Side Effects

Learn about the possible side effects of chemotherapy for breast cancer.

  • Neo-adjuvant chemotherapy may be used before surgery to reduce the size of large tumors and to destroy cancer cells. This type of chemotherapy may make breast-conserving surgery, such as a lumpectomy, possible. It also helps doctors understand how your tumor responds to different chemotherapy agents and treatment schedules, or regimens.
  • Adjuvant breast cancer chemotherapy, used after surgery or radiation, helps to further target breast cancer cells that may remain in the breast after primary treatment. It can also help prevent breast cancer from spreading to other parts of your body.
  • Port Placement

    If you’re receiving chemotherapy intravenously, your oncologist may implant a central port, or semi-permanent IV line, in your vein. This can help preserve your vein tissue from chemotherapy-related side effects and prevent you from having to get your vein punctured every time you receive medication.

  • Systemic breast cancer chemotherapy is designed to reach cancer cells throughout the entire body, not just the breast. It is normally used to treat people with more advanced breast cancer.

Most people with breast cancer receive a combination of drugs, which are given in cycles: a period of treatment followed by a period of recovery, then another treatment, and so on.

You may receive chemotherapy as an outpatient at a hospital, at the doctor's office, or at home. However, in some cases, depending on the particular regimen and your overall health, you may need to stay in the hospital during treatment.

Fractionated dose chemotherapy

With fractionated dose chemotherapy, the anti-cancer drugs are administered in small amounts over several days rather than in a single large dose as in standard chemotherapy. While the individual doses used in this approach are smaller than typical doses, giving them at frequent intervals can not only shrink the tumor by inhibiting the growth of the blood vessels that feed it, but may also destroy cancer cells.

Fractionated dose chemotherapy may also be less toxic and easier to tolerate than traditional chemotherapy, in which the maximum tolerated dose, or MTD is used. The maximum tolerated dose (MTD) is arrived at during clinical trials and is the highest dose of a chemotherapy agent that does not cause excessive toxicity or other side effects that are considered unacceptable.

Chemotherapy resistance testing

Before treatment begins, your doctors may perform a laboratory test to determine which combination of drugs is likely to be most effective against the particular type of breast cancer you have.

In chemotherapy resistance testing, a sample of your tumor is removed and tested to see how it reacts to a variety of anti-cancer drugs. If the tumor cells continue to grow after being exposed to a very strong dose of a particular agent, then it will almost certainly be resistant to breast cancer chemotherapy using that drug. On the other hand, if a particular agent slows or halts the growth of the tumor in laboratory testing, then chances are that the drug will be effective against the cancer.

Doctors generally use chemotherapy resistance testing with people who have solid breast cancer tumors and have been previously treated. Not only does testing point the way to effective treatment options for people who have been treated before. It’s especially valuable to help physicians decide which therapy to pursue when there’s a choice between two or more possible treatments that may be effective. It also helps limit exposure to potentially toxic chemotherapy agents that may not be effective for you.

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