Chemotherapy uses drugs to treat cancer, and radiation uses high-energy particles to destroy cancer cells. Both of these treatments may be used alone or in conjunction with other treatment options, according to the American Cancer Society.
Chemotherapy (chemo) drugs work in a number of different way. Alkylating agents work by damaging DNA, which prevents the cell from reproducing, and antimetabolites work by interfering with the way DNA and RNA cells grow. Anti-tumor antibiotics are unlike the antibiotics used to treat infections because they alter DNA inside cancer cells, which prevents them from growing and reproducing. Topoisomerase inhibitors are sometimes used as a form of chemotherapy, but they may increase the risk of another cancer, says the American Cancer Society. Chemo drugs are injected intravenously, and specific drugs are used on different types of cancer.
Like chemo, radiation may be used by itself or with other forms of treatment. Radiation treatment may be provided by a radiation oncologist or physician, and unlike chemo, radiation therapy involves one part of the body, the area in which the cancer is located. This treatment destroys cancer cells and leaves much of the rest of the body untouched. Generally, radiation is given in one of three ways