A test you should be getting instead of a colonoscopy

In the special “Ask the Insider” edition of Insiders’ Cures in May, I answered many good questions from readers, including one regarding how to ask your doctor about alternatives to colonoscopy. Now, important new data from Europe sheds more light on one of these alternatives: a groundbreaking procedure that truly offers safe, early detection of colon cancer—not to mention other serious health issues.

I’m talking about CT colonography (CTC). This simple test, also known as a virtual colonoscopy, can detect cancer and potentially cancerous polyps in the large intestine. Just like a colonoscopy can. But without the danger, invasiveness, expense, and flat-out discomfort of a colonoscopy.

In fact, a growing number of researchers are concluding that CTC is just as good as a colonoscopy at detecting colon cancer—but without all the risks.

Study after study shows the impressive accuracy of this new procedure. The European researchers analyzed six different studies on people with either average or high risk of colon cancer. And they found that CTC detected cancer in these people 96 percent of the time.1

Plus, this simple procedure can even help identify other life-threatening issues beyond colon cancer—before they become serious problems. Something a colonoscopy simply can’t do.

Cancer screening without the fuss

So how does CTC work? Well, you start with the same bowel-cleansing regimen you’d do before a colonoscopy. Your radiologist may also give you a laxative.

When you arrive for the procedure, the radiologist pumps some air into your colon so that it’s fully extended and can’t hide any polyps in folds or wrinkles. And then you get a 15-minute CT scan.

The CT scan uses x-rays to create a 3-D model of your colon, allowing the radiologist to see everything inside—including anything that looks remotely like cancer.

That’s it—no anesthetic, no invasive probes, no potentially contaminated endoscopes like you’d get with a colonoscopy. And some research shows that a CTC is also less expensive than a colonoscopy.

And, unlike a colonoscopy, a CTC can also find abnormalities outside the colon itself, in the abdominal cavity. Studies show that 10 to 15 percent of CTCs detect something outside of the colon that’s considered to be of moderate or high importance to the patient’s health.

These findings can include lymphoma and lung and kidney cancers—before they metastasize to other parts of the body. Not to mention abdominal aortic aneurysms (which may suddenly rupture and cause death) and masses on the adrenal glands.

These “incidental” findings save lives, reduce the healthcare burden, and prevent the development of more advanced diseases.

Not bad for a simple, noninvasive, 15-minute procedure.

But is it safe?

Research shows that CTC has a very low risk of major complications. You’re 20 times more likely to have symptomatic perforation of the colon during a colonoscopy than you are during a CTC.2 And, out of the few perforations that have occurred with CTCs, all but three were the result of an air-pumping technique that is no longer used.

There is, however, one potential risk that is higher in CTC than in a colonoscopy. As with all CT scans, CTC exposes you to radiation. Which could, ironically, lead to cancer.

But studies show that there’s really no need to worry about this radiation. In fact, one group of researchers estimated that people who get a CTC every five years from age 50 to 80 have only a 0.015 percent chance of getting cancer from the radiation.3

Plus, it’s important to note that the typical colon cancer screening intervals have increased to up to 10 years—making this theoretical risk even lower.

Scientists estimate at least an average of 30 colon cancers would be prevented for every radiation-induced cancer theoretically caused by the procedure.

Is there a better alternative?

Amazingly, the European researchers couldn’t directly compare CTCs to colonoscopies—because colonoscopies are so rare in Europe. But they did compare the accuracy, patient acceptance, and safety of CTC scans to two other colon cancer screening tests: stool examinations (fecal occult blood tests) and flexible sigmoidoscopy (a noninvasive way to examine the lower colon).

Simple stool tests and flexible sigmoidoscopy have already substantially reduced colon cancer death rates in our compatriots across the pond. And they are much safer screening alternatives compared to colonoscopies.

But although stool tests are completely safe and simple to perform, they primarily detect cancer after it has already become invasive.  Consequently, the researchers found that these tests typically reduce colon cancer death rates by only about 16 percent. (Cologuard, a new stool test I told you about in a September 23, 2014 Daily Dispatch, appears to detect cancer earlier, but is too new to have been included in this study.)

And while sigmoidoscopy reaches the most common sites of cancer in the lower colon, it is not able to see the entire colon. As a result, it typically reduces colon cancer deaths by 22 to 31 percent.

Because CTC is relatively new, there is little data yet on how much it affects death rates. But remember what I told you earlier: It can detect 96 percent of colon cancers. Not to mention the other life-threatening conditions it can find outside of your colon.

Of course, no screening test will work at all if people can’t be convinced to get it.  That’s why many realistic public health professionals say the best screening test is the one that people will actually go out and get. Considering the advantages CTC has over colonoscopy, it certainly appears to be an appealing option for patients. Whether or not doctors actually start recommending it is another matter entirely.

Chances are, you will have to specifically ask for this effective, noninvasive alternative. But it’s well worth making a special request.


1 “CT Colonography: Accuracy, Acceptance, Safety and Position in Organised Population Screening.” Gut 2015: 64(2); 342-350.

2 “Complications of CT colonography: a review.” Eur J Radiol 2013;82: 1159–1165.

3 “Radiation-related cancer risks from CT colonography screening: a risk-benefit analysis.” AJR Am J Roentgenol 2011; 196: 816–23.