Colon cancer is the third most common form of cancer in the United States. The American Cancer Society predicts more than a 100,000 new cases will be diagnosed this year.
But a new study in the New England Journal of Medicine confirms that standard tests like colonoscopies and removal of precancerous polyps can be effective in reducing colon cancer deaths.
MPR's medical analyst Dr. Jon Hallberg discussed the study's findings with Tom Crann of All Things Considered. Hallberg is a physician in family medicine at the University of Minnesota and medical director of the Mill City Clinic.
An edited transcript of that discussion is below.
Dr. Jon Hallberg: This is a large study that was done predominately in the United States. It found that by enrolling people in the study and looking for a certain kind of polyp — a growth inside the colon that can turn into colon cancer eventually — if you took those out, the endpoint was that they reduced colon cancer deaths from what they would expect by half.
Tom Crann: It's actually removing the polyp that's preventing death here?
Hallberg: If you can remove the polyp, you stop cancer from even setting in and taking hold. That's sort of what we want to be doing with this. If we're going to be detecting cancer, we want to catch it before it becomes a problem.
Crann: Why is it, in fact, showing some benefit, or more effective than we thought?
Hallberg: It has a lot to do with the nature of colon cancer. When you talk about breast cancer you should really say breast cancers, plural. Because there are lots of different kinds and they react and respond in different ways, but with colon cancer it's a little more homogenous...We know that colon cancer is typically very slow growing. So, that's why, if people have had colonoscopies, they'll do it once every ten years if they don't find any polyps.
Crann: We all know the test can be an ordeal, the preparation is unpleasant, is that in any way part of the reason it's so effective?
Hallberg: No. I think it really does get more at the nature of the cancer itself. The prep itself is just due to the fact that you're putting a scope in a colon, and you have to remove all fecal matter. If there's ever anything left behind, you might obscure a small polyp.
Crann: The test is disruptive and it's not pleasant for a lot of people. There was news about another test in the New England Journal of Medicine issue that is actually as effective, is that right?
Hallberg: You basically give a card to people to take home to collect a stool sample, mail it back and we test for the presence of blood. It's as simple as that. This test was as effective as colonoscopy in detecting colon cancer. It was much less effective though, of course, in detecting polyps, the precancerous things, so it's a very different kind of result.
Crann: Does this fact actually point the way that this test might change?
Hallberg: The test is used a lot these days... It's very cheap and people are more likely to do it. In that sense, coming up with a standard test that detects colon cancer, or pre-cancer, in a stool test, that is, I think, frankly, the Holy Grail. It would be relatively cheap; it's much more accepted, much easier to prepare for than doing a colonoscopy.
Crann: What has the reaction been in the clinic to a study that confirms what's already thought to be a good practice?
Hallberg: In the clinic and primary care it sort of confirms, more or less, the line that we've been giving our patients. My colleagues, who are gastroenterologists and colorectal cancer [doctors], it's a bit of a sigh of relief. They're sort of cheering that this study confirms what they're already doing.
Crann: Which is urging people to get screened?
Hallberg: That's the bottom line. People should get screened for colon cancer when they turn 50 if they don't have a strong family history of colon cancer. Which path you choose is up to you, but I think the bottom line message is [to] get screened.
Interview transcribed by Jon Collins, MPR reporter.