Colorectal carcinoma is the second most common cause of cancer deaths in the United States. This year approximately 60,000 Americans will die of colon cancer and approximately 120,000 new cases will be diagnosed. Colon cancer unlike most cancers is largely preventable. Most colon cancers begin as adenomas, which are small growths within the colon. These can become carcinoma over many years. It is estimated that it could take up to 10 years for a small polyp or adenoma to develop into invasive cancer. The size of the polyp correlates with the risk of the polyp being cancerous. Polyps less than 1 cm in size have less than a 1 percent chance of being cancerous, polyps between 1-2cm have an estimated risk of being cancer of 5 percent and those greater than 2 cm have a 10 percent risk of cancer.

There are many methods to screen for colorectal carcinoma. These include fecal occult blood testing (FOBT), sigmoidoscopy, barium enema, and optical colonoscopy. FOBT has limited sensitivity, sigmoidoscopy examines less than half of the colon, and although barium enema can be a sensitive study it can be difficult and time consuming both for the patient and the radiologist. Conventional optical colonoscopy is an excellent tool for detection of polyps. It is however not perfect and can miss 5-10 percent of polyps greater than 1 cm and 15 percent of polyps between 6-9 mm. Additionally not all colonoscopies are completely successful; the colon is incompletely visualized 5-10 percent of the time. Colonoscopy requires sedation, usually results in a loss of a day of work and there is also a small risk of perforation.

Unfortunately even with these multiple methods of screening for colon cancer few individuals are screened appropriately. Approximately 15 percent of patients who should be screened are screened. Many individuals do not wish to be sedated while some fear the placement of a large tube in the rectum and others do not want to undergo the bowel preparation that is required for screening.

There is a new type of screening examination now offered at Methodist Medical Center called CT colonography or virtual colonoscopy. This screening method uses a very fast CT scanner with software to look inside the colon. This sophisticated test is completed in less than 20 minutes and requires no sedation. Bowel preparation is required however and a small tube is placed into the rectum to distend the colon with air. When the study is completed there are no restrictions on the patient and the patient can drive to work. Virtual colonoscopy is sensitive in detection of the clinically significant polyps with a detection rate of greater than 90 percent for polyps greater than 1 cm in size. Additionally since CT scan of the abdomen and pelvis is performed other anatomic structures can be evaluated.

Men and women aged 50 and over should be screened. Those with a family history of colon cancer or a personal history inflammatory bowel disease should begin screening at an earlier age.
Patients with a personal history of colon cancer or polyps should have standard optical colonoscopy.

Currently, virtual colonoscopy is not covered by most insurance companies or Medicare. The current charge for a virtual colonoscopy at Methodist Medical Center is $750. If you would like to schedule an exam, please contact the scheduling department at 309-671-8282.