Long, long ago, in a galaxy far, far away, the Gastroenterology Empire’s primary weapon (and cash cow), the colonoscopy, was threatened by a Rebel Alliance of Radiologists. The result: Colonoscopy Wars!

A colonoscopy is strongly suggested for those over 50 (those over 40 would benefit) as it allows colon cancer to be detected, and like many cancers, eminently curable if detected early, and often fatal if not. The benefit here is well worth the unpleasantness of the procedure.

What does a colonoscopy do? It takes a look. There are two ways. Take an inside look by inserting a long tube-like gadget with a light, a camera, and a snipper into the colon. This is the “optical” method. Alternatively, the colon can be examined with a CT (“cat”) scan. This got named “Virtual Colonoscopy,” an unfortunate choice of terminology as it implies that it somehow isn’t real.

The cat scan is a radiology invention, and their intrusion into the sacred turf of the traditional $3000 colonoscopy was not well received. The battle was on. Technical papers were generated and hurled into the medical community with all due haste and vigor. Tempers flared. Stethoscopes slung.

Although the battle rages on, the Supreme Medical Dictator, (the insurance industry), seems to have ruled in favor of the optical variety. Specifically, although some private insurance covers a virtual colonoscopy, Medicare does not. An optical colonoscopy is always covered by both if you are over 50. This would seem to settle it. But, as it turns out, each side has several indisputable pros and cons.

Pros for Virtual

• Cheaper $500 versus $3000
• Less Unpleasant
• No general (or semi-general) anesthesia
• Able to look at both the inside and outside of the colon

Cons for Virtual

• Unable to take samples of suspicious areas (polyps). If any are spotted, an optical colonoscopy will then be needed.
• Insurance doesn’t cover it
• Radiation exposure

Pros for Optical

• Usually insured, though there may be a several hundred-dollar copay.
• Able to collect samples of suspicious areas for later analysis
• Able to find some very early stage cancers (called flat lesions) that the virtual colonoscopy cannot
• No radiation exposure

Cons for Optical

Depending on a physician’s predisposition, you will hear one method or the other touted as the “right” way. However, in terms of finding polyps, they are rather fairly equivalent. Furthermore, the radiation involved in the virtual method, if done with the latest model machine, is quite low, and the resolution is getting better and better. A CT or “cat” scan is an X-ray. It moves the X-ray around the patient mechanically, shooting a narrow beam through the patient from all angles.

Anyone going the “virtual” route should ask about the machine. Here are the questions to ask: First, try to find a center with an EBT machine. These are few and far between, but such machines move the X-ray beam electronically, which is much faster, and hence results in much less exposure. If no EBT machines are to be found, seek a CT (“cat”) machine with 256 slices or more. Cat machine are measured in slices, which basically means how many simultaneous X-ray images they can take as once. The more the better. A 256 slice machine exposes the patient to only a sixteenth the radiation as an older 16 slice machine. Actually, it’s lower still as sensor technology has improved as well. The 256 slice machines have such a low exposure that they are unlikely to cause any problems.

It seems to us that one might initially opt for the virtual version, but switch to the optical one if any problems were ever spotted. In any case, the overriding advice is: “do one of them.”

Why Bother with a Colonoscopy?

Colon cells are short-lived, turning over about every six days. This means very active replacement is going on, and hence a cancer risk. The stem cells that generate these replacement cells reside in “crypts,” small protected pouches found throughout the small intestine, colon, and rectum.

Should these cells become pre-cancerous, they will leave the crypt and erupt out of it. At this point it is called an adenoma and resembles a small bump. The bump can grow larger into a mushroom-like structure called a polyp. It is not necessarily cancerous at this time. In an optical colonoscopy, these are usually snipped off and examined. Less than 10% of polyps become cancerous, but virtually all colorectal cancer starts out as a polyp. Well, actually it starts as the aforementioned “bump,” which is where the issue of “flat’ lesions” comes up.

A cancerous polyp will initially be contained within the intestine (and easily treated), but with time, may grow through the intestinal wall or spread into the circulatory or lymphatic system (metastasize).

Screening for colon cancer means having a colonoscopy. Officially, this isn’t recommended for people under 50, but this is a mistake. A full 20% of people between 40 and 50 have some sort of abnormality that may become cancerous. This fact is known, but the medical reasoning is that it will be caught when these people have a colonoscopy at age 50. The insurance companies won’t pay, which seem a mistake, as early detection would save a lot of money (and lives.).

What Causes Colon Cancer

Not red meat. At least not healthily produced red meat. To look at associations of food with colon cancer, go to our China Study app, found here, select M029: COLORECTAL CANCER AGE 35-69 in the mortality box, and select a dietary item in the DIET box, for instance, D050: RED MEAT. Then click Plot. If the green trend line slopes down, it mean that more of the dietary item is associated with less of the mortality cause. I.e. the dietary item is protective. It the trend-line is upward, the dietary item associates with increased death. If the trend-line is flat, then no association. For red meat, the trend-line is flat, meaning no association.

Stool Samples

We started the post with galactic conflict, and will end it with the occult.

A third and completely non-intrusive method to screen is the Occult Fecal Sample. A stool sample from a cancerous colon may contain blood. No sorcerers are needed here. “Occult” simply mean hidden. I.e. a slight amount. The bleeding could come from anywhere in the digestive tract, starting with the mouth. There are other tests that may be performed on a stool sample.

Currently this sort of screening is not nearly as good at detecting cancer as either of the colonoscopies, but this could change as technology marches on. It is almost a certainty that cancerous material in the colon would find its way into a stool and potentially be detectable.

From Dr. Mike:

And this is where the coda to this piece comes in: yes, there are many emerging DNA based tests that look promising for early detection but we are not quit reliably there yet. And, yes, the above referenced ‘flat lesions’ are an argument for getting the optical scope—interesting side note: ‘flat lesions’ didn’t start showing up in the gastroenterology literature until the turf war between radiologists and gastroenterologists started heating up—however, if there is any hesitancy about getting an optical colonoscopy then get the virtual one. And as no one pays for colonoscopy for those under 50 get the virtual one and just pay for it.