So-called virtual colonoscopies - done using souped-up X-rays - detect tumours and pre-cancerous lesions almost as well as standard colonoscopies using a camera threaded through the colon, Italian researchers recently reported.
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.
1 in 83 SA men will get it
In South Africa colorectal cancer is among the top four most diagnosed cancers in the country with one in every 83 men, and one in every 131 women being diagnosed with it in their lifetime.
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.
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.
"Virtual colonoscopy does away with most of the objections patients have to colon screening and so helps improve compliance and thereby reduce the death toll from colorectal cancer," said Dr Clive Sperryn, president of the Radiological Society of South Africa (RSSA).
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 tumours 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 tumour, 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.
Colon screening in South Africa
Dr Sperryn said that colon screening was available from most radiology practices in South Africa.
The RSSA position statement on screening says that screening is appropriate and recommended for most people from age 50. A follow up should take place every five years. Either colonoscopy or virtual colonoscopy is acceptable as a screening tool. However, men at moderate risk and all high risk patients are advised to undergo conventional colonoscopy.
"We know that colorectal cancer is preventable. Yet the majority of the population susceptible to this disease remains unscreened. Increased use of VC will help save lives,” concluded Dr Sperryn. – (Maggie Fox/Reuters Health, Health24, June 2009)
Cancer in South Africa, 1998-1999. National Health Laboratory Service.
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