Chemotherapy (also called chemo) is a type of cancer treatment that uses drugs to destroy cancer cells.

Chemotherapy works by stopping or slowing the growth of cancer cells, which grow and divide quickly. But it can also harm healthy cells that divide quickly, such as those that line your mouth and intestines or cause your hair to grow. Damage to healthy cells may cause side effects. Often, side effects get better or go away after chemotherapy is over.

Depending on your type of cancer and how advanced it is, chemotherapy can:

• Destroy cancer - when chemotherapy destroys cancer cells to the point that your doctor can no longer detect them in your body and they will not grow back.
• Control cancer - when chemotherapy keeps cancer from spreading, slows its growth, or destroys cancer cells that have spread to other parts of your body.
• Ease cancer symptoms (also called palliative care) - when chemotherapy shrinks tumors that are causing pain or pressure.

Treatment schedules for chemotherapy vary widely. How often and how long you get chemotherapy depends on your type of cancer and how advanced it is, the goals of treatment (whether chemotherapy is used to cure your cancer, control its growth, or ease the symptoms), the type of chemotherapy and how your body reacts to it.

You may receive chemotherapy in cycles. A cycle is a period of chemotherapy treatment followed by a period of rest. For instance, you might receive 1 week of chemotherapy followed by 3 weeks of rest. These 4 weeks make up one cycle. The rest period gives your body a chance to build new healthy cells.

Chemotherapy may be given in many ways.

• Injection: The chemotherapy is given by a shot in a muscle in your arm, thigh, or hip or right under the skin in the fatty part of your arm, leg, or belly.
• Intra-arterial: The chemotherapy goes directly into the artery that is feeding the cancer.
• Intraperitoneal: The chemotherapy goes directly into the peritoneal cavity (the area that contains organs such as your intestines, stomach, liver, and ovaries).
• Intravenous (IV): The chemotherapy goes directly into a vein.
• Topically: The chemotherapy comes in a cream that you rub onto your skin.
• Orally: The chemotherapy comes in pills, capsules, or liquids that you swallow.