Chemotherapy is a systemic therapy , meaning that the drugs enter the bloodstream and travel through the body. Some anticancer drugs are given in the form of a pill. Radiation therapy is a local therapy , meaning that it affects the cancer cells only in the treated area. Most often it is used in patients whose cancer is in the rectum. Radiation therapy is also used to relieve symptoms.
Some patients have both kinds of radiation therapy.
Biological therapy , also called immunotherapy, uses the body's immune system to fight cancer. The immune system finds cancer cells in the body and works to destroy them. Biological therapies are used to repair, stimulate, or enhance the immune system's natural anticancer function. Biological therapy may be given after surgery, either alone or in combination with chemotherapy or radiation treatment. In some studies, all patients receive the new treatment.