Colorectal cancer will take nearly 50,000 lives the year, and is our country’s second largest killer. Screening is available, though there is a significant effort required in terms of preparation and the time needed to perform the test. For most people, the recommendation for your first colonoscopy is at age 50, though it may be sooner if you have risk factors for colon cancer or have noted any potential colon cancer symptoms.
If you’ve heard horror stories about colonoscopy, the test used today to screen for colon cancers, new technology may just save you from being someone who can tell them. There’s a new x-ray alternative that’s currently being studied by the American College of Radiology Imaging Network (ACRIN) National CT Colonography Trial and is showing itself to be effective at spotting most cancers.
The long anticipated study involved 15 medical centers across the U.S. and compared the accuracy of CT colonography to colonoscopy, the current gold standard of colon cancer diagnosis. The results of this study were published in the Sept. 18, 2008, issue of the New England Journal of Medicine.
A “virtual colonoscopy” (known technically as CT colonography) is a cheaper, less intrusive ‘super’ x-ray used for colon screening. The new test was able to pick up nine out of ten people who had large growths or cancers also detected by traditional colonoscopies. Of the false positives detected by the new type of scan, one in four turned out to be correct.
The new screening still involves some preparatory work i.e. cleaning the colon with laxatives or suppositories, just as you do today. You then go to a hospital radiology department to have the test, which takes about 10 minutes (compared to 30-60 minutes for colonoscopy). You lay first on your back and a thin tube is inserted into the rectum, air pumped in and then the table moved though the scanner, taking pictures all the time. You will then go through the scanner again, only this time lying on your stomach. After the two scans, a computer will process the images to create a picture of your lower digestive tract.
Unfortunately, radiologists can more easily misread the virtual colonoscopy. Polyps can be spotted that aren’t there, which may lead to unneeded follow up treatment and the terrible anguish of the threat of a serious health problem. However, sometimes the testing picks up other conditions, outside the colon, that wouldn’t have come to light that need to be addressed or investigated.
One other concern involves the amount of radiation you are exposed to during the test. The dose is half that of a standard CT scan, but experts worry about what this exposure means over time. Especially since this new test should be done every five years, as opposed to every ten years for traditional colon screening.
The new “virtual colonoscopy” seems to have the most value in getting people in for screening and identifying who may need further follow up. And early detection of colon cancer symptoms does save lives.