Chemotherapy is a type of medication that kills cells that are rapidly dividing. Many cancers grow and divide quickly and abnormally, making them good targets for chemotherapy. Unfortunately, some normal cells—such as skin, hair and blood cells and the cells that line the intestinal tract—also grow rapidly, and chemotherapy can kill these too. This can lead to many of the side effects that people on chemotherapy experience.
Oncologist can choose from many different chemotherapy drugs and regimens. A chemotherapy drug may be combined with another chemotherapy or with other types of treatments, including radiation, immunotherapy or targeted therapy. Each chemotherapy drug has different indications and side effects. Whether chemotherapy is used, and the type of chemotherapy used, may depend on the following:
- Your cancer type: Some types of cancer, such as ovarian and pancreatic cancer, are almost always treated with chemotherapy. Other cancers, such as breast cancer, may use chemotherapy for certain subtypes or stages of cancer.
- Your cancer stage and grade: Because of its many side effects, chemotherapy is often used on hard-to-treat or aggressive cancers that are likely to spread or have already spread to other parts of the body.
- For cancer that has spread, the location or site of cancer spread: Certain chemotherapy drugs may work better in different organs. For example, the blood-brain barrier protects your brain by filtering out drugs. If cancer has spread to your brain, your oncologist may treat you with chemotherapy that is able to cross the blood-brain barrier.
- Your general health and other medical conditions: Chemotherapy can cause many side effects. Some agents can affect the heart, liver, kidneys or other cells. Oncologists may choose specific chemotherapy agents for people with certain medical conditions, such as heart or kidney disease, to avoid further damage to these organs.
Chemotherapy is most often given as systemic therapy by injection into the veins or as a pill. This exposes the entire body to the drugs. In some cases, the medication may be given directly at the site of the cancer.
- Intraperitoneal (IP) chemotherapy involves injecting the chemotherapy directly into the abdomen. This approach is sometimes used to treat ovarian cancer. This allows doctors to deliver higher doses of chemotherapy to the cancer, while minimizing the rest of the body's exposure to these drugs.
- Topical chemotherapy is usually a cream or liquid that is applied directly to the cancer. Topical treatment is sometimes used to treat skin cancer.