What Is Chemotherapy for Cancer?

National Cancer Institute, Rhoda Baer (photographer)

Definition: Chemotherapy

Chemotherapy is the use of medications to kill cancer cells or make them less active.

Chemotherapy medications work by killing rapidly dividing cells. Since cancer cells divide more rapidly than most cells, they are particularly susceptible to treatment. Other cells that divide rapidly, such as hair follicles and the bone marrow cells that make blood cells, can also be affected; they account for many of the side effects of chemotherapy.

Chemotherapy is considered a "systemic" treatment, meaning that it works to kill cancer cells anywhere in the body. This differs from "local" treatments, such as surgery and radiation, which treat cancer in a particular area.

Chemotherapy may be used in several ways for cancer treatment:

  • To treat cancer that has spread (metastasized) to regions of the body distant from the tumor
  • As a "consolidation therapy," to shrink a tumor prior to another treatment such as surgery
  • As an adjuvant therapy, used along with a treatment such as surgery to treat any spread of cancer (micrometastases) that are too small to be detected on screening tests such as CT and MRI

Goals of Chemotherapy

Chemotherapy may be given for different reasons.  These include:

  • To cure cancer
  • To extend life when a cure is not possible
  • To relieve the symptoms of cancer

Further Reading:

Examples: After Don had surgery for his lung cancer, his doctor recommended chemotherapy to treat any cancer cells that may have spread beyond the area of his surgery.

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