So-called virtual colonoscopies — done using souped-up x-rays — detect tumors and precancerous lesions almost as well as standard colonoscopies using a camera threaded through the colon, Italian researchers reported on Tuesday.
The virtual procedure, done using computed tomography scans, might offer an alternative for people who are embarrassed or afraid to have a standard colonoscopy and encourage them to be examined, Dr Daniele Regge of the Institute for Cancer Research and Treatment in Turin, Italy, and colleagues said.
Their study, published in the Journal of the American Medical Association, adds to a growing body of evidence showing the CT procedures are safe and almost as good as standard colonoscopies.
Colon cancer is the second-biggest cancer killer in most countries, after lung cancer.
It is easily detected at earlier and more treatable stages using colonoscopy — a tiny camera threaded up through the rectum. The device has a little pair of clippers on the end to remove suspicious-looking growths called polyps so they can be tested to see if they might become cancerous.
U.S. health experts recommend regular colonoscopies for people starting at age 50 and the practice is credited with helping to lower the number of deaths from colon cancer from around 52,000 in 2007 to just under 50,000 people this year in the United States.
But only about half of those who should get them do, in part because the procedure is embarrassing, uncomfortable and can, in rare cases, cause injury.
Regge's team tested more than 1,000 people, giving each both a real and virtual colonoscopy on the same day.
The x-rays found 151 of the 177 patients who had advanced neoplasia — the lesions most likely to become tumors if not removed.
"CT colonography detected 39 of 41 participants with cancer, including all 3 with diameters of 6 to 9 mm," they wrote.
If the CT scan finds a polyp or tumor, the patients must have a standard colonoscopy to get a sample, but people who are cleared can escape being sedated and having the procedure.
With either procedure, patients must take strong laxatives and the virtual procedure requires having some air puffed into the colon, so it is not entirely comfortable, either.
"Computed tomographic colonography has been shown to be better accepted than colonoscopy and has a negligible risk of serious adverse events; thus, it may help increase the low adherence reported for individuals who are candidates for screening, which is the main negative factor affecting its efficacy in reducing mortality from colorectal cancer," Regge's team wrote.
"With the majority of individuals in the United States who meet criteria for colorectal cancer screening and surveillance not undergoing recommended procedures, an imperfect test that has a lower risk profile and greater acceptance among patients seems to be an appealing solution," Dr Emily Finlayson of the University of Michigan agreed in a commentary.
In May Medicare, the U.S. federal health insurance plan for the elderly and disabled, said it would not pay for virtual colonoscopies.
New Hampshire-based iCAD Inc is one company providing computer-aided detection or CT colonography equipment.