Chemotherapy uses “anticancer” drugs to destroy cancer cells by stopping them from growing or multiplying. Healthy cells can also be harmed, especially those that divide quickly. Harm to healthy cells is what causes side effects. These cells usually repair themselves after chemotherapy.

Chemotherapy can be either the primary cancer treatment (used alone or in combination with other types of treatment) or used to prevent the return of cancer following a primary therapy such as surgery or radiation therapy.

Because some drugs work better together than alone, often two or more drugs are given at the same time. This is called combination chemotherapy. Which drugs are used is based on what kind of cancer you have, where the cancer is located, the effect of the cancer on your normal body functions and your general health.

The drugs can be administered in several ways:

• By Mouth  The drug is given in pill, capsule or liquid form. You swallow the drug, just as you do many other medicines.
• By Injection  A needle and syringe are used to give the drug in one of several ways: Intramuscularly (into a muscle), Subcutaneously (under the skin) or Intralesionally (directly into a cancerous area in the skin) or, most commonly, Intravenously.
• Intravenous Chemotherapy is most often given by a thin needle inserted into a vein on the hand or lower arm at the beginning of each treatment session and is removed at the end of the session. Chemotherapy can also be delivered intravenously through catheters, ports and pumps.
• By Application to the Skin  The drug is applied on the surface of the skin.

Your oncologist will select the method based on what’s best for your type of cancer. The duration of each treatment depends on the method and the number and amount of medications prescribed. You may get treatment every day, every week or every month. Chemotherapy is often given in cycles that include treatment periods alternated with rest periods that give your body a chance to build healthy new cells and regain its strength. How often and how long you get chemotherapy will depend on the type of cancer, treatment goals, drugs being used and how your body responds to them.

The actual administration of the chemotherapy itself does not hurt, though the treatment may cause some uncomfortable side effects such as nausea and/or vomiting, appetite loss, hair loss, anemia and fatigue.

For further information on chemotherapy, visit the National Cancer Institute's guide Chemotherapy and You: A Guide to Self-Help During Cancer Treatment.