Radiation therapy is usually performed on an outpatient basis and works by damaging the cancer cells, thereby reducing or eliminating their ability to reproduce or grow. The objective of radiation therapy is to eliminate enough cancer cells to maximize the probability of a cure and minimize any side effects. There are typically two forms of radiation therapy - internal radiation (brachytherapy) and external radiation.
Both internal and external radiation focuses radiation energy on the parts of the body where cancer cells are located. Radiation therapy, unlike chemotherapy, is considered a local treatment. This means the cancer cells are only killed at the location in the body where the radiation is delivered, called the radiation field.