Revisiting Cancer Screening — the Colonoscopy Conundrum
The latest news on lifesaving colon cancer screening missed one huge point: The best test is the one you actually get, not the one you might have gotten but never did. That makes your options for cancer screening a little more complicated and interesting, but still vital to your health.
I sort out the confusion in this newsletter. Read on for more.
Colonoscopy Saves Lives but Only If You Get One
Would you take a free medical test if it promised a good chance at saving your life? Of course, you say, but reality might be … well, not so much, at least when it comes to screening for colon cancer.
Proof of this came in a little-noticed aspect of an important new study on colon cancer screening from doctors in Spain, published in the New England Journal of Medicine. They offered free colonoscopies or a stool test called fecal immunochemical testing (FIT) to thousands of people.
Only one in four patients took them up on the offer for a free colonoscopy. One in three patients took the FIT test when offered.
The statistics in the United States are similar, and is it any wonder? As I wrote about colon cancer screening a few newsletters back:
The colon is the body’s factory for stool, so the idea of probing into it is nasty, unpleasant and best avoided if unnecessary.
But now things have changed. We finally have solid evidence that colonoscopy done once every ten years saves lives — evidence that even a few months ago was only wishful thinking. And the evidence of beating cancer with colonoscopy is far stronger than for some other cancer screening tests — such as the PSA test for prostate and mammograms for breast.
In another new study on colonoscopy published in the same issue of the New England Journal of Medicine, the researchers followed 2,600 people who had pre-cancerous polyps removed from their colons with colonoscopy. Instead of the expected 25 deaths from colon cancer that they would have expected in any average group of 2,600 people, only 12 people died from colon cancer.
(This was the source of all the headlines you might have seen about cutting the death rate by more than 50 percent. It’s actually more like a reduction from one in 1,000 to one in 2,000, but it’s still an impressive number.)
But every one of those 2,600 people in the study did have the colonoscopy. If three of four had declined the test, as in the Spanish study, the results would have been a lot less impressive.
Bottom line: Your odds of beating colon cancer with a good test are a lot less if you never get the test.
Another Reasonable Option for Colon Cancer Screening
The FIT test is a lot less trouble than colonoscopy. FIT is a modern, more specific (less chance of a “false positive” from having eaten bloody meat or from bleeding in your stomach) version of the old fecal occult blood test, where you had to poke a stick into your bowel production in the toilet bowl, and then wipe it on a piece of paper and send to the lab. That’s only a few minutes of unpleasantness.
For colonoscopy, on the other hand, you have to clean out the entire colon. That means swallowing large quantities of a fairly nasty liquid laxative, then spending a lot of time sitting on the toilet until it “runs clear,” and then fasting from anything but clear liquids until you get the actual test. The test involves sedating you on an operating table and then running a flexible scope the entire five-foot length of your colon.
The new study from Spain mentioned above found that the FIT test is likely going to turn out to be a reasonable option to colonoscopy — but again, only for those folks who follow through and actually get it done.
Here’s the tradeoff: You only need a colonoscopy every ten years. That’s because if the doctor sees pre-cancerous polyps, the doctor can snip them off during the test. But the FIT test only detects actual bleeding cancers, not the pre-cancerous growths. So for it to be a safe option, you need it every two years minimum, and the American Cancer Society says every year.
There are other options besides colonoscopy and the FIT test, but those are the two best. And because colonoscopy can treat at the same time it detects, that’s the very best.
But only if you get it. Got it?
Some sources for further information published in our earlier newsletter on colon cancer screening are still good: the National Cancer Institute, and for real in depth discussion, the comparison discussion from the National Guideline Clearinghouse.
To your continued health!
Patrick Malone & Associates