The word "radiation" doesn't seem to belong with "therapy." We tend to think of radiation as something to avoid at all costs. We associate it with atomic bombs, too much sun, and standing too close to the microwave. In truth, though, we're all exposed to radiation. The things we've added to our world (radios, walkie-talkies, x-rays) emit radiation -- so does the Earth itself. Each of us absorbs some radiation every day just by living on this planet.
It's not good for us, but we deal with it. People who receive radiation therapy as a treatment for colon cancer are in a similar situation. Patients may receive radiation therapy before surgery to shrink the tumor, after surgery to help prevent the tumor from coming back, or instead of surgery to destroy cancer cells in tumors that can't be surgically removed.
External radiation is the most common type used in colon cancer treatment. Radiation treatments are quick but frequent -- a few minutes a day, five days a week, for many weeks.
For information about other ways to treat colon cancer, please read Colon Cancer Treatment Options.
Source: "Detailed Guide: Colon and Rectum Cancer: How Is Colorectal Cancer Treated?" American Cancer Society 22 Feb. 2006. Accessed 21 Jul. 2007