There is little question in the minds of many experts that we could do a much better job of diagnosing certain cancers earlier, resulting in more effective treatments and better survivals.
When it comes to colorectal cancer, we simply don’t do a great job of screening for the disease. Colorectal cancer is a topic that people don’t normally want to talk about, yet the potential for reducing deaths from this cancer has been estimated in the tens of thousands each year—if we only did what we already know.
If we started effectively screening the people age 50 and over in this country tomorrow, we would cut deaths from this disease substantially and reasonably quickly.
And, in the case of colorectal cancer, we are not just talking about effectively treating the disease. We are talking about possibly preventing it in the first place.
That’s why an article in today’s New England Journal of Medicine is so interesting, and potentially so important.
The “traditional” methods for colorectal cancer screening include a test called fecal occult blood test, sigmoidoscopy, barium enema and colonoscopy either used as a stand-alone test, or in specific combinations (such as sigmoidoscopy every five years in conjunction with FOBT every year).
Each of these tests has their pros and cons, and each is not welcome by some (if not many) patients who have to complete the test.
FOBT—whether done with the older slide test called a “guaiac test” or the newer and more specific immunochemical version--is the “old standby.” Barium enema has faded fast from the scene (although they are still done in some parts of the country). Sigmoidoscopy has lost favor, and colonoscopy has been gaining advocates.
Although some physicians and patients have a strong preference for one test or the other, the bottom line is that the best test for you is the one you get.
For several years, researchers have been trying to come up with a test that will be more acceptable to patients, and result in a larger number of people getting screened. The most promising new technologies are DNA testing of stool samples (which the patient collects and ships to the lab) for evidence of colorectal cancer, and using CT scans instead of colonoscopes to find polyps and cancers in the colon.
DNA testing is actually available for patients to use, but CT colonography (or “virtual” colonoscopy, as some people call it) is still in the research phase.
In the New England Journal paper, the researchers examined the medical records of over 3000 patients who underwent routine colonoscopy to screen for colorectal cancer, and another 3000+ patients who underwent CT colonography.
The results of the study showed that both methods detected an almost equal number of advanced polyps (that is, polyps that were on their way to becoming a cancer). For reasons that are not known, the group that had CT colonography had more colon cancers found when compared to the routine colonoscopy group.
However, in the routine standard colonoscopy group, there were many more polyps removed (2434) compared to the CT colonography group (561). In the standard group, the colonoscope perforated the bowel in seven cases. There were no similar perforations in the CT group.
Why the big difference in the number of polyps removed? First, it is important to note that if the polyp was 1 cm in size or greater, the patient was referred immediately for routine colonoscopy and polyp removal.
If the polyp was between 6 and 9 mm, the patient was offered either same day colonoscopy for removal, or follow-up CT colonoscopy.
Smaller polyps have a lesser chance of turning into cancer, and—of the 404 patients who underwent the CT study and had a positive finding--158 with small polyps elected to have ongoing CT surveillance, and not proceed directly to polyp removal.
The implications of this study suggest that using CT colonography to screen for colorectal cancer may allow more people to be screened with equal effectiveness compared to the standard colonoscopy test, and permit a more targeted approach to detection of advanced polyps and colorectal cancers.
That would be welcome news, but as always there are always cautionary factors that must be noted.
My American Cancer Society colleague, Dr. Durado Brooks (who is our expert on colorectal cancer and colorectal cancer screening) points out that one of the limitations of the study is that we are comparing groups of patients, as opposed to doing both tests on the same patients.
And, perhaps most important in understanding whether or not this approach is ready for widespread use across the country, Dr. Brooks points out that these procedures were performed at a single center, and the CT scans were interpreted by a group of radiologists who have had considerable experience in reading these studies.
Dr. Brooks concludes with the note that there is an upcoming publication of a study that looked directly at a comparison of CT colonography and standard screening colonoscopy for colorectal cancer. The report from that study is eagerly awaited, and will likely have a significant influence on whether or not CT colonography is ready for wider utilization.
So this NEJM report is an interesting one, but not yet sufficient to recommend that people routinely consider CT colonography as a screening test for colorectal cancer.
We still have a way to go to validate the effectiveness of this approach in a community setting, which is where this test is likely to be performed. As with many tests and new procedures, the results that are found in a research study where the doctors have a large interest in a particular test do not directly translate into the community when the use of the test diffuses throughout the country.
Hopefully, we will have the answers we seek in the near future after the results of the clinical trial are made available. And, hopefully, we will be able to assure the public that the standards that have made the test successful in academic centers are applied equally in community settings.
And then there is the greater hope, namely that no matter what test is available, that people will do something to get screened for colorectal cancer.
We lose too many people every year because they don’t get screened. Having another test may increase the options for screening, but ultimately you still need to make the decision to get screened, make the visit to the doctor and get the test.
Whatever test, the one you get is the one that may save your life.