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You’re listening to Clinician's Roundtable on ReachMD, and this episode is sponsored by Exact Sciences. Here’s your host, Dr. Charles Turck.
This is Clinician’s Roundtable on ReachMD, and I'm Dr. Charles Turck. Joining me today to discuss a poster he presented at the 2023 American College of Gastroenterology Annual Scientific Meeting is Dr. Nicholas Talabiska. He's a PGY-3 internal medicine resident at Temple University Hospital in Philadelphia, and his poster focused on discordant results between multi-target stool DNA tests and follow-up colonoscopies. Dr. Talabiska, thanks for being here today.
Absolutely. Thanks for having me. I'm excited to be here.
So if we start with some background, Dr. Talabiska, would you give us an overview of the available screening options and protocols for colorectal cancer?
Absolutely. So the way I like to think about it is I make two different groups. The first being direct visualization, and that's going to include things like colonoscopy and flexible sigmoidoscopy. These are both procedures that use flexible scopes to be able to look at the lumen of the bowel. They can give different recommendations based on what's found, but ultimately, those can range from 1 to 3 to 5, 7, and 10 years depending on what's seen. From there, we also have some stool-based tests that can be used. One of those is the multi-target stool DNA tests. These tests look at things like genes that are commonly mutated in colorectal cancer and common methylated genes that are also seen in colorectal cancer, and then it also has a simple FIT test, which looks at a breakdown of essentially hemoglobin products within stool. And then there are fecal immunochemical tests and also guaiac-based tests, which are looking for breakdown products of blood and stool, which can also be used for recommendations for further screening.
Now if a patient receives a positive result from their multi-target stool DNA test but then a negative result from their colonoscopy, what kind of dilemma or challenge does that pose, and how did it lead you to conduct your research?
Yeah, I mean this is the million-dollar question right here. When we think about discordant studies—just like you said, someone has a positive multi-target stool DNA test and then a negative screening colonoscopy—ultimately, the question is going to be, “What do we do with these patients going forward? Do we consider them higher risk? Should they come back more often? Do they need more testing?” And really that's what led me to want to study this; there was no formal recommendations on how to treat these patients. As a medical student, I remember hearing many different clinicians say how this made them uncomfortable to give this person a clean bill of health for 10 years before they needed another screening colonoscopy. So ultimately, I thought it was just a great place that needed some more research.
And what study methods did you use to investigate these discordant test results?
So this study specifically was really just a simple retrospective chart review. We outlined a bunch of variables that we were interested in looking at within this cohort of patients and then looked at them across the board, saw what was similar with them, what was different, and if there was anything that could have been correlated ultimately with their discordant tests.
Those just tuning in, you're listening to Clinician’s Roundtable on ReachMD. I'm Dr. Charles Turck, and I'm speaking with Dr. Nicholas Talabiska about a poster he presented at the 2023 ACG Annual Scientific Meeting that examined discordant results between multi-target stool DNA testing and colonoscopy.
Now if we zero in on the results, Dr. Talabiska, would you give us a breakdown of the patient demographic data?
Yeah, absolutely. So from this specific cohort in this study, we saw that there were 420 patients who met our inclusion criteria. There's a slightly more predominance of women with there being 251 compared to 189 men. And then really the two predominant ethnicities that we saw were Caucasian and African American.
And how about the procedure results? What were the key findings there?
So out of these 420 patients, there were actually about 100 patients who technically did not meet criteria for appropriateness in getting a multi-target stool DNA test, whether that was based on personal or family history. Now there were 228 negative multi-target stool DNA tests, and we did follow these patients as well to see if there was any interval colon cancer development, which was not seen out of these 228. Out of the 420, there were 192 that had a positive test. And then there were subsequently 165 of those that actually completed a sentinel screening colonoscopy. Within those, there were 103 discordant studies and with those, there were six cases of interval colon cancer development as we followed those patients across time. This was about a 5.8 percent development of interval colon cancer within those discordant studies that actually had some follow-up studies. From there, we also wanted to look at some of the recommendations that were being given to those patients, and it's interesting, there really did not seem to be any sort of consensus on what screening follow-up period the patient was getting. So for example, we saw that there were 13 patients that were given 1 year, 30 patients that were given 3 years, 39 patients that were given 5 years, and 16 patients that were given 10 years. So it was very split, and we saw a lot within that middle period. Not many got the full 10 years before follow-up. And then lastly, we really just wanted to look at other factors that were seen on the colonoscopy. So we looked at things like internal and external hemorrhoids and diverticular disease, and interestingly, we saw over half of the patients that had discordant studies had one of these or some sort of combination seen on colonoscopy.
And lastly, Dr. Talabiska, where do we go from here? What are clinicians to do when they encounter patients like these who have discordant test results?
Well, prior to 2021, this was really the dilemma that we were talking about earlier. There was no recommended guideline for what these patients should be given in terms of continued surveillance. Luckily in 2021, the USPSTF came out with formal recommendations saying that even in patients that have had discordant studies, they should ultimately be given surveillance intervals based on the colonoscopy that they had as long as it was a good quality study that had a good bowel prep and they were able to reach the cecum and intubate the terminal ileum. And I still think although that's where we're at, some of those studies were not all that high powered. And that was one of our goals here was to try and give a little bit more information to try and make clinicians a little bit more comfortable with that formal recommendation.
Well, with those important considerations in mind, I want to thank my guest, Dr. Nicholas Talabiska, for joining me to discuss the poster he presented on discordant results between multi-target stool DNA testing and colonoscopy. Dr. Talabiska, it was great having you on the program.
It was an absolute pleasure. Thank you for having me.
This episode of Clinician's Roundtable was sponsored by Exact Sciences. To access this and other episodes in our series, visitClinician's Roundtable on ReachMD.com, where you can Be Part of the Knowledge. Thanks for listening!
