According to an article recently published in the New England Journal of Medicine, virtual colonoscopy, also referred to as computed tomographic colonography (CTC), is an effective initial screening measure for the detection of colorectal cancer.
Colorectal cancer is the second leading cause of cancer-related deaths in the United States. If detected and treated early, colorectal cancer is highly curable. Thus screening for colorectal cancer is recommended starting at the age of 50 for individuals with a normal risk of developing the disease and earlier for those at higher risk.
Historically, optical colonoscopy (OC) has been the mainstay of screening for colorectal cancer. An OC is a procedure in which a lighted tube with an attached camera is inserted into the rectum and through the colon. During the colonoscopy the physician is able to view the colon on a screen and is able to remove abnormal-looking areas or growths. Unfortunately, patients often view an OC as invasive and time-consuming, which results in a low compliance rate.
CTC is another screening procedure for colorectal cancer. CTC uses computed tomography to scan the colon. Results from research have been conflicting about the effectiveness of CTC in detecting colorectal cancer compared to OC. However, physicians are optimistic that compliance rates may increase with CTC because it is not as invasive as OC.
Researchers from the University of Wisconsin recently conducted a clinical trial to compare OC to CTC for the detection of colorectal cancer. This trial included approximately 3,300 adults with an average age of 57–58 years. Patients underwent either initial screening with CTC or initial screening with OC. Patients initially screened with CTC in whom polyps (small growths) at least 6 millimeters in size were detected were offered a polypectomy (removal of polyps) with OC. As well, patients with one or two polyps between 6 and 9 millimeters were offered the option of CTC surveillance (repeated scans at specified intervals to detect growth).
- Among patients initially receiving CTC, nearly 8% were referred to undergo a subsequent OC.
- Advanced neoplasia (abnormal cellular growth often preceding cancer) was detected in 3.2% of patients who underwent an initial CTC and 3.4% of patients who underwent an initial OC.
- Approximately one-quarter of the polyps were removed among patients who underwent a CTC compared with those who underwent an initial OC.
The researchers concluded: “Primary CTC and OC screening strategies resulted in similar detection rates for advanced neoplasia, although the numbers of polypectomies and complications were considerably smaller in the CTC group. These findings support the use of CTC as a primary screening test before therapeutic OC.” Individuals may wish speak with their healthcare provider about screening schedules for colorectal cancer.
Reference: Kim D, Pickhardt P, Taylor A, et al. CT colonography versus colonoscopy for the detection of advanced neoplasia. The New England Journal of Medicine. 2007;357:1403-1412.