Explain what factors determine whether an oncologist treats cancer with chemotherapy, radiation or a combination of the two.

Treatment of cancer by either chemotherapy or radiation depends on the type of cancer, the stage of cancer when the patient is diagnosed, and the patient’s overall health. This is because either option may make more sense, or may be more effective, than the other. Chemotherapy is a systemic remedy and therefore used to treat cancers that have metastasized. Radiation, on the other hand, is localized and used to treat cancer at early stages.