According to a recent article published in the journal Radiology, virtual colonoscopy appears to accurately detect large polyps in the colon.
When detected early, colorectal cancer is a highly curable disease. Colorectal cancer typically begins with the development of an adenomatous polyp, which is a small benign tumor that grows in the colon. These polyps often take 10 to 15 years to transform into cancer. Since this development phase is so long, screening and early detection can play a crucial role in the prevention of colorectal cancer, as detection and removal of the polyps can prevent the development of the disease.
A colonoscopy, which involves patient sedation and the insertion of a lighted tube into the large intestine, is currently the most effective means to detect pre-cancerous polyps as well as early-stage colon cancers. However, many patients do not want to undergo this invasive procedure, which involves bowel cleansing, sedation and a small risk of perforation of the intestine. Therefore, researchers have been investigating novel approaches to detect pre-cancerous polyps while minimizing the invasiveness associated with a colonoscopy.
Virtual colonoscopy is a technique that utilizes a type of computerized tomography (CT) scanning and sophisticated computer programs to produce images of the inside of the large intestine. Researchers from the New York University Medical Center recently conducted a clinical trial to directly compare virtual colonoscopy to actual colonoscopy in 105 patients. The patients underwent a virtual colonoscopy immediately before an actual colonoscopy and the results were compared. Virtual colonoscopy detected 93% of polyps larger than 10 millimeters (mm), 70% of polyps between 6 and 9 mm and only 12% of polyps smaller than 5 mm. Virtual colonoscopy did not inaccurately detect any polyps that were not seen with the actual colonoscopy.
These results indicate that virtual colonoscopy appears to detect large polyps with considerable accuracy. However, smaller polyps detected with an actual colonoscopy were not detected with much accuracy with a virtual colonoscopy. Future research may include evaluating the accuracy of combining results from a virtual colonoscopy, sigmoidoscopy and fecal occult blood test (FOBT) as a screening procedure for the future. Patients who are to undergo a colonoscopy may wish to speak with their physician about the risks and benefits of participating in a clinical trial further evaluating screening procedures. Two sources of information regarding ongoing clinical trials include the National Cancer Institute ( cancer.gov) and www.eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients.
Reference: Macari M, Bini E, Xue X, et al. Colorectal neoplasms: prospective comparison of thin-section low-dose multi-detector row CT colonography and conventional colonoscopy for detection.