You may have heard of something called a “virtual colonoscopy,” which is often advertised as a less invasive colon cancer-screening method—an alternative to a full-on colonoscopy. But are these “virtual” tests just as effective at spotting colon cancer? We asked the experts, and the answer we received was that both screening methods can detect colon cancer, but when it comes to finding very early signs of cancer, including the smaller colon polyps that can turn into cancer down the line, the virtual colonoscopies are not quite as effective. There is a reason why the regular, full colonoscopy is still the gold standard for early detection of cancer.
So What is a “Virtual Colonoscopy”?Read More
Unlike a traditional colonoscopy, a virtual colonoscopy doesn’t require anesthesia or sedatives. You remain awake during the test, and it only takes about 10 minutes.
With a traditional colonoscopy, on the other hand, a doctor inserts a flexible tube with a camera on it (called a colonoscope) into the anus and uses it to look at the full length of your colon and rectum. Usually, patients getting this colonoscopy will get “put under” with anesthesia or given relaxing sedatives to minimize the discomfort.
Dr. Heather Yeo, a colorectal surgeon at NewYork-Presbyterian/Weill Cornell Medical Center and a medical advisor to SurvivorNet, explained that some patients have health conditions or complications that prevent them from receiving anesthesia, and some patients have other conditions (such as blocked colons) that make it impossible to insert the colonoscope needed for a traditional colonoscopy. For these patients, Dr. Yeo said, a virtual colonoscopy is a good alternative for cancer screenings.
Dr. Yeo has also had patients in the past who refuse to have a colonoscopy because they don’t like the idea of inserting the colonoscope. For these patients, too, Dr. Yeo said the virtual test can be an option.
“For cancer screening purposes, it’s better to have a virtual than nothing,” Dr. Yeo said.
That being said, if you don’t have any health reasons to forego a traditional colonoscopy (and assuming you have someone who can pick you up from the test afterward, since you will have been sedated and therefore unable to drive), Dr. Yeo said the full-on test is the better bet.
For one—and this is a really important point—if your doctors spot something abnormal on a virtual colonoscopy, chances are you’ll have to get a colonoscopy next anyway. You’ll end up doing two tests when you could’ve done just one.
“There’s no ‘one’ screening test for colon cancer,” Dr. Yeo said. “There are several different methods, including stool tests and CT tests. But the general issue with these tests is that if you find something, you still have to do the full one.” (“Full one” being the traditional colonoscopy with the colonoscope).
Secondly, traditional colonoscopies can spot really small polyps (under 5-6 mm) that might turn into cancer down the line. “The smaller the polyp, the harder it is to detect,” Dr. Yeo said. “Usually polyps under 5-6 millimeters are hard to pick up on a [virtual] CT colonography.”
Of course there are variables in the traditional colonoscopy that can make it hard to see a tiny polyp, too—such as the skill level of the person conducting the colonoscopy, or how well someone adhered to the colon prep directions (drinking clear liquids the day before, for instance.)
If your doctors spot a polyp during your traditional colonoscopy, they can usually remove it right then and there, and send it to a pathology lab to test for cancerous cells. If your doctors spot one of these on the virtual colonoscopy, they’d have to schedule you for the full-on colonoscopy to do the same.
Another Reason To Stick With the Traditional Colonoscopy if You Can: The Dreaded “Prep” Is The Same
For many people, the most uncomfortable part of a colonoscopy isn’t the test itself, but rather the day-before “prep.”
To effectively spot cancer, polyps, or anything abnormal, your colon needs to be completely “cleaned out.” That means that the day before the test, you’ll probably have to drink only clear liquids and take whatever combination of laxatives and enemas your doctor recommends.
It’s not pleasant to clear out your colon, but it’s worth it when you think about the alternative—that is, missing a life-threatening cancer.
When it comes to detecting colon cancer, Dr. Yeo said, “CT [virtual colonoscopies] and scope [traditional colonoscopies] are both not great if the prep isn’t great.”
The “less invasive” colon screening option—the virtual kind—still requires this prep. You’ll still have to drink clear liquids and clear out your colon.
Also, if the thought of any sort of instrument being inserted into your rectum makes you squeamish, don’t assume you’ll get to avoid this altogether during a virtual colonoscopy. Turns out doctors will still need to insert an instrument in the virtual kind (to puff up your colon with air, making the walls easier to see.)
What Do the Guidelines Say?
The American Cancer Society currently recommends that people with an average risk of colon cancer beginning getting screened at age 45. With the traditional colonoscopy, the test is repeated once every 10 years, but with the virtual colonoscopy, it’s repeated every 5 years.
Of course, screening recommendations can vary depending on risk factors, symptoms, and whether you have polyps (which can require more frequent colonoscopies).
So in general, full-on colonoscopies are the better bet when it comes to detecting cancer. But if for whatever reason you can’t have one, the virtual colonoscopy can still make a lifesaving difference. The bottom line, Dr. Yeo said, is that getting screened for colon cancer—regardless of the method—is a must.
“Colon cancer is considered a ‘silent and deadly’ killer,” Dr. Yeo told SurvivorNet in a previous conversation about screenings. “What happens is that people often don’t know that they have colon cancer. They don’t have any symptoms. That’s why we screen for colon cancer in the United States.”