It s one of the most dreaded aspects of a recommended preventive medical schedule: the colonoscopy. But a new study, published in the Annals of Internal Medicine, suggests that virtual colonoscopy without the harsh laxative bowel preparation, and which doesn t use a scope, might be just as effective as regular colonoscopy at detecting polyps in the colon as long as the polyps are large enough, that is.
A researcher from Massachusetts General Hospital and colleagues analyzed the data derived from over 600 adults ages 50 to 85 after each had undergone both a virtual and a standard colonoscopy over the course of five weeks. The results showed that, for polyps (adenomas) at least 10 mm in size, virtual colonoscopy without laxative preparation was able to correctly identify 91 percent of cases. This number did not differ significantly from the rate of 95 percent obtained with standard colonoscopy. However, the virtual colonoscopy was significantly less effective at identifying smaller polyps in the 6 to 8 mm range.
It s important to note, however, that the vast majority of polyps that lead to cancer and affect survival outcomes are at least 10 mm in size. For this reason, the researchers concluded that laxative-free virtual colonoscopy might be an important option to help improve access to colon cancer screening, considering that many adults avoid colonoscopies because of the discomfort of the necessary preparation. For this type of virtual colonoscopy, patients were required only to eat a low-fiber diet and an oral contrast material before the procedure. In fact, of the patients involved in this study, 62 percent said that they would choose the virtual method in the future.
ACSH's Dr. Elizabeth Whelan, however, remains concerned that those patients who choose a virtual colonoscopy without laxative preparation may be receiving a false sense of security, due to the relatively high false negative rate for smaller polyps. It concerns me that this procedure does not pick up smaller lesions, she notes.
But as ACSH's Dr. Gilbert Ross explains, The key part of this story is that the vast majority of polyps that lead to cancer mortality are at least 10 mm, which is the size that the virtual procedure can identify well. So this test is going to be picking up most pre-cancerous lesions. He adds, If this is going to increase the number of people receiving colon cancer screening by two- or three-fold, this will save many lives. But a regular colonoscopy is still the gold standard.