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Conditions & Treatments |
Colon Cancer | PolypsCondition What is colon cancer?Each year, approximately 150,000 Americans are diagnosed with a very common and serious disease - colon cancer. Colon cancer, also called large bowel cancer, is the term used to describe malignant tumors found in the colon and rectum. The colon and rectum are part of the large intestine of the digestive system, usually referred to as the gastrointestinal tract. Typically, the colon is the upper 5 or 6 feet of the large intestine, and the rectum is the lower 5 to 7 inches located above the anal canal. Colon cancer usually develops within benign growths called polyps, which arise from the colon wall. If polyps are detected early, removing them stops the development of cancer. The current gold-standard technique for finding and removing polyps is endoscopy, a procedure in which a long, flexible tube is inserted into the colon, allowing a doctor to search for and remove polyps. Unfortunately, many people are either unwilling or unable to undergo endoscopy and are therefore not screened for polyps. ScreeningWhat type of screening is available for colon cancer?CT Colonography (CTC) is used to screen patients for colon cancer and polyps. CT Colonography sometimes called "Virtual Colonoscopy", is a new minimally-invasive and easily tolerated technique by which patients receive a special CT (or "CAT") scan. When should I consider CT Colonography? A polyp can form at any time throughout life, but most commonly occurs in people over the age of 50. Most polyps grow slowly, and the risk that cancer will be found in a polyp is substantial only for polyps greater than 6mm in size. If your CTC shows no polyps, we will recommend that you wait five years before having another CTC. Recently the American Cancer Society endorsed CT Colonography as a screening test for colorectal cancer. It is now considered to be a valuable alternative to endoscopy because it is less invasive and does not require sedation or time off from work. What should I expect BEFORE CT Colonography? The bowel preparation that you take the night before your appointment is essential for a good exam. The colon needs to be prepared so that the radiologist can clearly see if any polyps are present. The special liquid that you drink passes through you and is not absorbed by your body. Because the liquid is not absorbed, it causes most people to have diarrhea on that evening only. On the morning of the exam, you should strictly limit your diet to clear liquids, such as tea or apple juice. (Please note: questions surrounding your current medication usage will be addressed at the time of scheduling.) You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure. Metal objects including jewelry, eyeglasses, dentures and hairpins may affect the CT images and should be left at home or removed prior to your exam. You may also be asked to remove hearing aids and removable dental work. What should I expect DURING CT Colonography? A CT scan is an X-ray test that creates special images of the body. The images from the CT scan are transferred to a computer, which creates a detailed set of 3D pictures of the colon. A radiologist (a doctor who specializes in medical imaging) is then able to evaluate the colon on the computer, looking for the same polyps that can be seen with conventional endoscopy. CTC is designed to be easily tolerated by patients. The entire exam can be completed within twenty minutes, and most patients report that it causes little or no discomfort. To begin, you will lie comfortably on the CT scanner table. A very small, flexible tube is inserted into the rectum and some air is gently blown into the colon to hold it open. After the tube is inserted, your privacy will be maintained and you will be in control of the amount of air. You may experience a temporary sense of fullness and bloating, but nearly all patients report that the air insufflation is not painful. It takes about two minutes to perform the actual CT scan. The first series of pictures will be taken with you lying on your back, followed by another set lying on your stomach. After the pictures are taken, the tube is removed and the exam is complete. Because no sedation is required for the test, you can drive or return to work after the exam is completed. Immediately following the exam, you may resume your regular diet. What should I expect AFTER CT Colonography? Most people don't have polyps, but the smaller percentage of people who do should have them removed. If we detect a polyp on your CTC, we will inform your doctor, and he or she will likely recommend a conventional colonscopy (endoscopy) to have the polyp removed. Some patients may elect to have a conventional colonoscopy following their CTC exam. Our ServiceThe Division of Abdominal Imaging & Intervention at Massachusetts General Hospital consists of 20 full-time abdominal imaging radiologists all of whom are board-certified in radiology with additional specialization in abdominal imaging.An abdominal radiologist specialty trained to supervise and interpret CT Colonography examinations will analyze the images and send a signed report to your physician, who will then share the results with you. Please see below for the abdominal radiologist who specializes in CT Colonography: Where is CT Colonography performed?
A referral from a physician is necessary to make an appointment. Physicians may schedule patients using our online scheduling and report access program - ROE. For detailed information, please contact the CTC Coordinator(s):
To assist with scheduling please have the following information ready when calling:
Additional Information and Resources
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