Today, the American Cancer Society released its latest recommendations for the prevention and early detection of colorectal cancer.
The published guidelines offer a detailed roadmap on what works in colorectal cancer screening. They include the same approaches that have been recommended in the past—including testing the stool for blood, sigmoidoscopy, colonoscopy and barium enema—and add two new approaches to the “recommended list” with the addition of CT colonography and stool DNA testing.
The experts who analyzed the data and made these recommendations made an important new distinction about tests used to screen for CRC by sorting the available screening tests into two categories: tests that are primarily used to detect colorectal cancer (CRC), and tests that have the potential to prevent colorectal cancer.
They also indicated their preference was for tests that prevent this disease.
Here is what the authors say about what you should do: “It is the strong opinion that colon cancer prevention should be the primary goal of CRC screening. Tests that are designed to detect both early cancer and adenomatous polyps should be encouraged if resources are available and patients are willing to undergo an invasive test.”
What many people don’t realize is that if we followed these guidelines, we could save thousands of lives every year.
The guidelines themselves are available online, along with a report that goes into great detail about which tests are recommended and why, as well as the strengths, limitations and possible harms of each test.
These are guideline recommendations for screening people age 50 and older at average risk of developing CRC. They are not for people at high risk because of other diseases, genetic abnormalities or family history of CRC. In those circumstances, you need to check out the high risk screening recommendations found on our web site.
Another important point is that—just like the previous guidelines—the best test for you is the one you get and the one you are most comfortable with. Making a decision may be easier for some people than others, but you need to make the decision in consultation with your health care professional.
Now on to the tests themselves.
Testing a series of stool specimens at home with the tried and true approach using guaiac cards (fecal occult blood test, or FOBT) remains an option, but only if the “sensitive” cards are used (your doctor will understand what that means). These tests are inexpensive and widely available.
Using a more patient friendly stool test called fecal immunochemical testing (or FIT) is also an option for screening. This test is also more specific for finding colon cancer, and doesn’t require the limits on your diet before you do the test, as is the recommendation for FOBT.
There are important cautions with these tests, namely that you must follow the instructions carefully regarding dietary restrictions for the FOBT, and making certain you get samples from consecutive bowel movements. Doing the test in your doctor’s office after a rectal exam (for men, it’s usually with a prostate exam and for women as part of their routine annual checkup) is not screening for CRC and should be discouraged!!!
Also, both of these tests only work effectively to find CRC and some large polyps if you do the test every year.
Which brings us to another new wrinkle in these guidelines.
In order to be considered effective in either detecting or preventing CRC, each test when done once must be able to find CRC at least 50% of the time when the disease is present.
It would be reasonable to ask if that is acceptable. After all, don’t you want a test that will find cancer 100% of the time?
The answer from the report is that it may not be ideal, but at least it’s a standard to consider when evaluating a particular test. More importantly, it also points out why it is so important with the FOBT and FIT tests that you repeat whichever one you use every year. That repetition is what makes these tests work and gives you the best chance of finding CRC when it can be cured.
A new test recommended for the detection of cancer (and not prevention) is a stool DNA test. This test is much more expensive than the others, and requires collecting an entire bowel movement and sending it to the lab for analysis. The lab then processes the sample and looks for gene markers in the stool sample that are consistent with cancer in the bowel.
Research shows that—perhaps contrary to what you would think—patients seem to accept this test. It meets the “50%” criteria noted above, however no one knows how often it should be repeated. As noted in the guidelines report, the company recommends repeating this every 5 years. However, there is no scientific evidence to back that recommendation. The bottom line is we don’t know how often it should be done to be maximally effective in detecting CRC.
Another problem with this test—as with FOBT and FIT—is that it detects cancer, not polyps (except in occasional situations). Consequently, it is not a test that prevents cancer, but rather it is one that may find a cancer that is already present.
The next category of tests—which is the preferred approach—includes sigmoidoscopy, barium enema, colonoscopy and CT colonography.
Barium enema is infrequently performed today as a screening test.
Similarly, the use of sigmoidoscopy is declining as a screening test for a variety of reasons including discomfort, the assumption that colonoscopy is more effective since it looks at the entire colon, and because few physicians are trained to do it well. In addition, the new guidelines say that if your doctor does a screening sigmoidoscopy, she/he should be able to remove any polyps they see. Few primary care physicians are capable of doing that properly.
Colonoscopy has developed a reputation as the “gold standard” for CRC screening, since the doctor can evaluate the entire colon and remove most polyps that are seen. But not everyone can get a colonoscopy for any number of reasons, and some people don’t want to have a colonoscopy primarily because of the prep and the fact that they need to take time off from work. Others can’t afford it, don’t have insurance, or have insurance that doesn’t cover colonoscopy as a screening test.
The report also points out that, despite the designation of this test as “the best test” by many doctors and patients, it is still not a perfect test.
There is concern about the time the doctor takes to do the test: the longer she/he takes, the better the results. But many doctors pride themselves on how quickly they can do the test.
In addition, what many people don’t know is that colonoscopy is not 100% perfect at finding all polyps and all cancers.
Yes, studies do show that screening colonoscopy and removing pre-cancerous polyps reduce the incidence of CRC, but not 100% according to the guidelines report. In fact, in one study the incidence of CRC within 5 years after colonoscopy was down about 50%, and over 10 years about 72%. That’s pretty good, but a far cry from 100% that many doctors and patients assume to be the case.
Other studies show that colonoscopy misses large adenomas (precancerous benign growths) in the bowel 6 to 12% of the time, and misses actual cancers about 5% of time.
So, although colonoscopy is certainly an excellent test for CRC screening, it doesn’t find every polyp before it becomes cancerous. Still, it is a very effective test in preventing CRC.
The other “new kid on the block” in these recommendations is CT colonography (CTC).
In this test, using new up-to-date technology, you can get a CT scan which has an excellent chance of finding pre-cancerous polyps and actual cancers. The test is done on a CT machine after the same prep used for regular colonoscopy. It is quick, and does not require sedation. There may be pain or discomfort from the air they have to pump into your colon at the time of the test.
The problem is what to do about polyps that are found during the study.
If you are fortunate to have access to a radiology and GI practice that work together, you may be able to get a same day colonoscopy if the radiologist sees something on the scan.
If you are not so fortunate, you have to come back another day to get your regular colonoscopy—after going through another full bowel prep.
Research studies performed by radiologists who were very experienced in doing CTC show that this procedure is about as effective as regular colonoscopy when it comes to finding larger polyps and cancers.
Given the fact that we don’t know as much as we would like to about the effectiveness of CTC, the guidelines recommend repeating the study every 5 years if the initial CTC is negative.
As I mentioned earlier, the test you get is the one that is best for you.
The guidelines’ authors recommend that your first-line choice should be a test that both prevents and detects colorectal cancer. These include barium enema, sigmoidoscopy, regular colonoscopy and CT colonography.
Tests that are primary designed to detect cancer but not prevent it are acceptable, but not the first choice of the guidelines. These include annual FOBT, annual FIT, and stool DNA (but we don’t know how often this new test should be done).
But—as recently pointed out in the Presidential campaign—these are “just words.”
The words in this report do have meaning, but they only exist on paper. To make them do something for you, you need to do something for yourself.
You need to make the decision to get screened for colorectal cancer, and you need to do it now.
I hope I live to see the day when everyone who needs to be screened for this disease takes advantage of that opportunity. We will never be able to prevent every colorectal cancer, or catch every colorectal cancer early when it has a very high chance of being cured.
What we can do is save thousands of lives every year, year after year if we only do what we already know works.
Now, I ask you: Is that asking too much?
I don’t think so.