Chemotherapy is often the first choice for treating many cancers. It differs from surgery or radiation in that it is almost always used as a systemic treatment. This means the medicines travel throughout the body to reach cancer cells wherever they may have spread. Treatments like radiation and surgery act in a specific area such as the breast, lung, or colon, and so are considered local treatments.
You and your doctor will decide what drug or combination of drugs you will get. Your doctor usually chooses the doses, how the drugs will be given, and how often, and how long a treatment is best for you. All of these decisions will depend on the type and location of the cancer, its size, and how it is affecting your normal body functions and overall health.