The Clinical Consequences of Delayed Colorectal Cancer Screening

Dr. Buch:
You're listening to Clinician's Roundtable on ReachMD. I'm Dr. Peter Buch, and joining me to discuss the clinical consequences of delayed or missed colorectal cancer screening is Dr. Christopher Cann. He's an Assistant Professor in the Department of Hematology Oncology at Fox Chase Cancer Center in Philadelphia, where he's also the Director of the Young Adult Cancer Program.  Dr. Cann, welcome to the program.

Dr. Cann:
Thanks so much for having me. It's a pleasure.

Dr. Buch:
To start us off, Dr. Cann, it is well known that colon cancer screening reduces the incidence of colon cancer. What is the range of reduction when using colonoscopy, stool tests, and blood tests?

Dr. Cann:
I think the way that I like to think about it is really thinking about the sensitivity and specificity of these ranges of types of tests. So colonoscopy, as many of you know, is the gold standard. And so we're thinking of a sensitivity of picking up a neoplasia at around 95 percent when you're doing the recommended screening interval.

But as we move towards different testing—so the FIT testing or the DNA testing—the sensitivities somewhat decrease. So for example, a quantitative FIT testing has a sensitivity around 74 percent. So we're losing a significant amount of sensitivity there as well. And these DNA tests are slightly more sensitive than that.

But why I like to bring this up is because it reinforces the fact that although going through a procedure such as a colonoscopy may be a little arduous for some people, especially the prep, the importance of this can't be understated in the sense that this can pick up these cancers pretty darn well. And so we are able to act on them at an earlier stage.

Dr. Buch:
Dr. Cann, can you tell us a little bit about the sensitivity and specificity of the recently available blood testing?

Dr. Cann:
So from my understanding, for the circulating free DNA testing that has been brought out—although I have not necessarily seen it used ubiquitously in clinical practice as of yet; it still has some work to go, but we're getting there—the sensitivity ranges around 83 to 85 percent for colon cancer specifically.

Now, for the advanced pre-cancerous polyps, on the other hand, that's a lot lower; that's at 13 to 15 percent. So what that tells us is that it's pretty good at picking up a cancerous lesion within the blood. However, it's not very good at picking up these precancerous lesions, and so this would likely require you to get this more frequently if you were relying solely on this.

I do have hopes that this eventually will improve over the course of time and may limit the amount of invasive testing we have to do, but at this point, it does not replace the gold standard colonoscopy.

Dr. Buch:
Thank you for that information. So by contrast, what are the statistics when the tests that we just talked about—colonoscopies, stool tests, and blood tests—are delayed?

Dr. Cann:
So I think this is one of the things that I wish was more ubiquitously discussed in the sense that delaying screenings does increase your risk for the development of colon cancer. Even a 12-month delay can increase the risk of advanced cancer by almost two times. What we found is that each additional month of delay is associated with a 3 percent increased risk of death related to that colon cancer.

Another example of this is that risks rise notably around after 16 months, with some studies showing a roughly 33 percent increase in advanced cancer diagnoses compared to those who adhere to the guidelines. So all that being said, it just reinforces the importance of abiding by the screening guidelines because even what may seemingly be a small delay in obtaining a colonoscopy or any of those screening methodologies is  potentially increasing your risk of an advanced, potentially incurable cancer significantly.

Dr. Buch:
Thank you. For those just tuning in, you're listening to Clinician's Roundtable on ReachMD. I'm Dr. Peter Buch, and I'm speaking with Dr. Christopher Cann about the importance of timely colorectal cancer screening.

So, Dr. Cann, building on that, let's shift to the patient perspective. What are some of the most common reasons patients fall behind on recommended colorectal cancer screening?

Dr. Cann:
I think one thing that people always bring up to me is really the fear of undergoing a colonoscopy for a variety of reasons. One is the anesthesia. Two is the risk of perforation of the colon, which is very low, but is real. So I always try to acknowledge that as best I can. And the other component is the prep; people do not want to spend their day or night in the bathroom making sure that their bowels are clear to have a good visualization. And so those fears and logistical issues definitely cause patients to be more wary about getting that. The other component of this is essentially taking a day off from work or school to be able to get this procedure done. It puts this screening test off for patients because it is arduous in the sense of having to potentially miss a day of pay to undergo this type of screening.

And that's why I'm thankful that there are less invasive ways to get screening; they are not as sensitive as a colonoscopy, but they at least provide some form of screening so that if it does return positive, there is a very low threshold to then pursue that colonoscopy moving forward.

Dr. Buch:
Perfect. I want to just throw a couple of other issues in your direction about why patients fall behind. Can you address cultural issues and how that affects the answer to that question?

Dr. Cann:
So I think from a cultural standpoint, if there's any issues or concerns of having any type of medical procedure, that is when it comes to potential need of blood products if there are any issues there, or if there are concerns when it comes to any visualization of the colon because of a cultural or religious background.

I think that is really where physicians and providers at large need to be able to discuss with patients directly, acknowledge their concerns, and ask about their concerns so that we can find ways to get around the potential inability to obtain a colonoscopy so that we can then provide them with other avenues, such as stool sample testing or blood sample testing. So at least we provide some form of methodology to screen them for this so that we can act upon it because it's that important that we can prevent life-limiting disease with some rather simple methodologies.

Dr. Buch:
Some patients are just so concerned about colon cancer equating with colostomy that they just don't want to have it done. Can you address that from your perspective?

Dr. Cann:
I think that's a really great point. Colostomies from a patient perspective can be really a drastic change in quality of life in the sense that there is something you're always having to deal with when it comes to your stool that people can become self-conscious of. Body image issues can absolutely be a real problem, but what I would say is that screening colonoscopies and these tests are designed to hopefully prevent that exact outcome in the sense that if we were able to catch a polyp at its early stage as precancerous and resect it right then and there with a colonoscopy, we're avoiding the implications of a potential larger tumor that would necessitate you to have a surgery and then potentially have that colostomy. So we can say, "Oh, I completely understand and hear the reservations of, 'what if we do find a tumor that requires me to have this?' The goal of these screening tests is to prevent that exact problem in the sense of catching something early enough that we can get rid of it to avoid these quality-of-life implications down the road.

Dr. Buch:
How do patient outcomes differ when colorectal cancer is caught early versus at a more advanced stage?

Dr. Cann:
I think that's a great question because it directly ties into why screening is so important. Generally speaking, colon cancer, when caught early and not in that stage four setting, is curable. There obviously are graded risks based upon the stage at which it's caught and about the risk of recurrence, but our goal here is that we prevent cancers.

But even if things are delayed and we catch a cancer early enough—within that stage two to stage three range—our goal is to resect that tumor and cure you of that cancer. When it comes to stage four cancers or cancer that's spread to other organs, it makes the chance of cure a lot smaller or not able to be cured.

And so that then lends us to be requiring things like chemotherapy to help reduce the risk of its spreading, to keep the tumor under control, and prolong life and quality of life as long as we can. So the goals being if we were able to catch these tumors and polyps early enough, we can try to cure someone versus having to deal with a more lifelong and life-limiting illness if it's caught too late and is in that stage four range.

Dr. Buch:
Thank you for that information, Dr. Cann. What strategies or interventions have shown promise in reducing delays in colorectal cancer screening and improving early detection rates?

Dr. Cann:
I think that one of the biggest things that I've seen improve is spreading the awareness of colon cancer within the community and showing people these screening methodologies—what options there are and that they don't necessarily always have to go and say colonoscopies is the end all-be all if they really are afraid of pursuing a colonoscopy at that time—and providing FIT testing awareness. I know at our institution, they had an outreach program providing FIT tests to people in the community of North Philadelphia. And it really improved the amount of potential screening that we had for patients that wouldn't have normally been able to have the time or the ability to get these colonoscopies done.

And so I think one of the biggest things that we can do as providers is to spread the awareness of colorectal cancer screening when it's recommended, but also that there are different modalities that we can use that may allow us to potentially avoid colonoscopy if there's a big reservation regarding that, but also allow us to minimally invasively recognize if there’s a real chance of cancer developing so that we can expedite their evaluation moving forward.

Dr. Buch:
With those final thoughts in mind, I want thank my guest, Dr. Christopher Cann, for joining me to discuss how timely colorectal cancer screening can improve outcomes for patients. Dr. Cann, it was great having you on the program.

Dr. Cann:
Thanks again for having me. I appreciate it.

Dr. Buch:
For ReachMD, I'm Dr. Peter Buch. To access this and other episodes in our series, visit Clinician's Roundtable on ReachMD.com, where you can Be Part of the Knowledge.