Colon cancer is the second leading cause of cancer death in men and women. Colon cancer takes a long time (10-15 years) to develop from precancerous polyps. Patients with polyps often do not have symptoms; symptoms only become apparent when the cancer is more advanced and less effectively treatable. CT Colonography is a new type of x-ray exam that applies the well-know CT technique for examining the interior of the colon, or large intestines. It is a non-invasive and accurate examination which detect early precancerous polyps. The prognosis for early colon cancer is excellent.