How chemotherapy works

How chemotherapy works

Chemotherapy treats many different types of cancer. This video explains how chemotherapy works.

How chemotherapy works

How chemotherapy works 

Voice-over: Chemotherapy, sometimes called chemo, is a cancer treatment that uses drugs to target rapidly dividing cells throughout your whole body.  

Chemotherapy can be given in different ways such as into a vein or by mouth. It kills cancer cells, but it also damages healthy cells.  

Different chemotherapy drugs treat different cancers. Your healthcare team will create a treatment plan just for you, based on your health and the cancer. You may have more than one chemotherapy drug. This is called a combination.  

Combinations often work better than a single drug, but they also damage more cells and can cause more severe side effects. A course of chemotherapy is made up of several cycles. In each cycle, you have treatment and then a rest period. For example, a cycle may be 3 days of chemotherapy followed by 25 days of rest.  

During the rest period, your healthy cells repair themselves and your body recovers. But cancer cells can’t repair themselves, so they die. The number of cycles and the length of each cycle depend on your treatment plan. You’ll have blood tests before starting treatment to see what your normal blood counts are.  

Blood counts show the number of different blood cells. Chemotherapy kills blood cells, causing your blood counts to drop. But as you recover from treatment, they usually return to normal. Doctors will order blood tests throughout your treatment to see how chemotherapy is affecting your organs and how well your body is recovering.  

The timing of your blood tests before each treatment is important to see if it’s safe for you to have chemotherapy. If your blood counts are too low or your organs aren’t working well, your team may delay chemotherapy or reduce the amount you are receiving. It’s important to go to your follow-up appointments during chemotherapy. Ask your doctor questions and tell them your concerns about treatment or side effects.  

The Canadian Cancer Society is also here to help. Visit or call us at 1-888-939-3333.