Chemotherapy is the treatment of cancerous diseases with drugs that interfere with the cancer cell growth and reproduction. Normal cells grow and die in a controlled way, but when cancer occurs, the cancer cells keep dividing and forming more cancer cells. Chemotherapy destroys cancer cells by preventing them from growing or multiplying. Cancer chemotherapy may consist of a single drug or a combinations of drugs, and can be administered through a vein, injected into a body cavity or delivered orally in the form of a pill. Chemotherapy drugs circulate in the blood to parts of the body where the cancer may have spread and can kill or eliminate cancer cells at sites great distances from the original cancer. As a result, chemotherapy is considered a systemic treatment.
Chemotherapy cannot distinguish between cancer cells and healthy cells. Chemotherapy damages rapidly dividing cells, a hallmark trait of cancer cells. However in the process, healthy cells that are also rapidly dividing, such as blood cells and the cells lining the mouth and GI tract are also damaged. Treatment-related damage to healthy cells leads to complications of treatment, or side effects. These side effects may be severe, reducing a patient’s quality of life, compromising their ability to receive their full, prescribed treatment, and sometimes, limiting their chance for an optimal outcome from treatment.
Hormones are naturally occurring substances in the body that stimulate the growth of hormone sensitive tissues, such as the breast or prostate gland. When cancer arises in breast or prostate tissue, its growth and spread may be caused by the body’s own hormones. Therefore, drugs that block hormone production or change the way hormones work, and/or removal of organs that secrete hormones, such as the ovaries or testicles, are ways of fighting cancer. Hormone therapy, similar to chemotherapy, is a systemic treatment in that it may affect cancer cells throughout the body.
A targeted therapy is one that is designed to treat only the cancer cells and minimize damage to normal, healthy cells. Cancer treatments that “target” cancer cells may offer the advantage of reduced treatment-related side effects and improved outcomes.
Biological therapy is referred to by many terms, including immunologic therapy, immunotherapy, or biotherapy. Biological therapy is a type of treatment that uses the body’s immune system to facilitate the killing of cancer cells. Types of biological therapy include interferon, interleukin, monoclonal antibodies, colony stimulating factors (cytokines), and vaccines.