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Chemotherapy (also called "chemo" or "anti-cancer drugs") are drugs used to kill cancer cells. If there’s a moderate or high risk of cancer cells in the local area, chemotherapy may be used to try to kill the cells. There are risks that the cancer cells have travelled to other parts of the body. 

Unlike radiation therapy, which focuses on a specific part of the body, chemotherapy treats the whole body. This means that the drugs may affect normal cells as well. Most chemo is administered intravenously.

How it works

Chemotherapy destroys cancer cells in two ways:

  • By stopping cancer cells from growing or multiplying.

  • By causing spontaneous cell death. 

There are many chemotherapy drugs used today. Because each works in different ways, you may get a combination of drugs to take. This is known as combination therapy.

Because chemotherapy works on the whole body, if you have a cancer that has spread to different parts of the body, the chemotherapy may reach it. Depending on the type of cancer being treated, you can get chemotherapy in a number of ways:

Intravenously: through an IV, you’ll receive chemotherapy through a needle placed in your vein. The IV can be placed and removed with each treatment, or you may want to consider a venous access device.

Venous access device: a thin tube is placed in a large vein in your chest or arm. Your chemotherapy is given to you through this tube, also often called a port. This device may be left in your vein for weeks or months at a time and reduces the number of needles you need.


The treatment schedule

Your treatment schedule will depend on the type of chemotherapy regimen you and your doctor decide is best. A standard chemotherapy regimen can last from three to six months. The chemo may be given weekly – every two or three weeks. Chemo is divided into “cycles” which usually range from four to six cycles of chemo over a cycle length of 28 days (or four weeks). Your treatment may be interrupted because of illness or other health conditions.  

Who may benefit from chemotherapy?

Persons with a moderate to high risk of the cancer coming back, despite good surgery. Also, for tumours which have features that will respond positively to chemotherapy, this treatment may be recommended.

When is chemotherapy used?

Chemotherapy can be used in all stages of breast cancer for various reasons:

  • Cancer has returned to the breast area
  • Cancer has spread to other parts of the body
  • Cancer has a high risk of returning
  • In early stage breast cancer, chemotherapy may be used as adjuvant therapy, or in combination with other targeted treatments. That is, after surgery is completed, chemotherapy is used for two reasons: to get rid of any cancer cells that may be left behind; and to reduce the risk of the cancer coming back (reccurence).

Chemotherapy can also be used for patients who are HER2-positive or whose breast cancer is considered triple negative.
Chemotherapy is recommended when the benefits outweigh the risks and when the patient is healthy enough to take the treatment.
Chemotherapy works best when the schedule is maintained but adjustments may be needed based on the safety and well-being of the patient. For tumours that are hormone sensitive, there are specific tests to determine if chemo will be of benefit.