Cancer cells multiply faster than normal cells in the body. Because radiation is most harmful to quickly growing cells, radiation therapy damages cancer cells more than normal cells. This prevents the cancer cells from growing and dividing, and leads to cell death. Related Theory Characteristics of cancer cells - Uncontrolled potential to divide and do not response to programmed cell death, or apoptosis. - Show Metastasis i.e., they can migrate and spread to other organs and tissues by travelling through the bloodstream. - Angiogenesis is the formation of new blood vessels from existing blood vessels to meet their high oxygen demand. - shows chromosomal abnormalities