• Colon and Rectal Cancers - Prognosis
• Highlights
• Introduction
• Causes
• Risk Factors and Prevention
• Symptoms
• Diagnosis and Screening

Radiation

Radiation therapy uses x-rays to kill cancer cells that might remain after an operation or to shrink large tumors before an operation so that they can be removed surgically. The object of radiation therapy is to damage the tumor as much as possible without harming surrounding tissues. Radiation may be administered in one of the following two ways:

• Externally from a source outside the body, such as a linear accelerator (external beam radiation)
• Internally through small radioactive pellets...