Philip Schoenfeld, MD: Quality Indicators in Colorectal Cancer Screening With Colonoscopy

In an interview with MD Magazine® at ACG 2019, Philip Schoenfeld, MD, MSEd, MSc, chief of gastroenterology at John D. Dingell VA Medical Center, discusses the benefits of quality indicators in colorectal cancer screening with colonoscopy.

Schoenfeld: I'm here today to discuss quality indicators in colorectal cancer screening with colonoscopy. Specifically, I'm going to discuss the quality indicator for getting an adequate bowel prep, as well as the quality indicator for compliance with recommending a 10-year interval after a normal screening colonoscopy. Let's start with the issue of bowel preparation. I think we all understand the importance of doing a split-dose bowel preparation. And you may prefer to use Miralax/Gatorade or Suprep or Plenvu or a 4-liter GoLytely split prep. What we have virtually no data about is what you should do if a patient has previously failed a 4-liter GoLytely split prep. I know that many gastroenterologists will recommend 2 days of clear liquids, or may recommend that a patient use magnesium citrate 2 days before their procedure along with GoLytely. In fact, there's no retrospective or prospective data to look at how commonly that produces inadequate bowel prep.

In research presented here [at ACG], patients who had previously failed a 4-liter GoLytely prep were recommended or prescribed 4 liters of GoLytely to take on the day before the procedure, 2 liters of GoLytely to take on the morning of the procedure, and staying on clear liquid simply for the day before the procedure. In intention-to-treat analysis, 88% of those difficult-to-manage patients had an adequate bowel preparation based on the Boston Bowel Preparation scale. Now certainly this is a high volume of GoLytely to consume, and it should probably be reserved for those patients who've had a history of inadequate bowel preparation in the past. Nevertheless, this is the first study to report a specific bowel preparation to use for those patients who have failed a 4-liter GoLytely prep.

Now this is important because you have to have an adequate bowel prep in order to recommend a 10-year interval for the average risk patient who has had a normal screening colonoscopy. We have multiple studies that show if a patient has a fair bowel preparation, something less than an excellent bowel preparation, clinicians will frequently recommend that the patient come back at 5 years instead of 10 years. There's a fallacy to this management. The fallacy is that gastroenterologists think that even if I might have missed the polyp because the bowel preparation was only fair, that if I bring the patient at 5 years, I will be able to diagnose a large polyp that I might have missed sooner before that large polyp can develop into a cancer. We now have excellent data from the VA Cooperative 380 study…and we see that patients who had a normal screening colonoscopy develop interval cancer within 3 and a half years of when they had their normal screening colonoscopy. That's because most of those interval cancers occur because a large flat adenoma or large flat serrated polyp were missed in the ascending colon. The bottom line here is that if you have a normal screening colonoscopy, and the prep is fair, and you recommend a repeat in 5 years, you're probably not going to prevent an interval cancer since the majority of patients who get interval cancer have it occur within 3 and a half years. If they have 1 or 2 small adenomas with a fair prep, then interval cancer occurs within 24 months. So how do we manage this issue?

The task force on bowel preparation, which is part of the Multi-Society Task Force on Colorectal Cancer Screening, recommends that you repeat a colonoscopy within 12 months if the prep is not adequate. Now that's a difficult situation for a gastroenterologist to face. It's kind of like being between a rock and a hard place because if you repeat a colonoscopy within 12 months, you're not going to get full payment for doing 2 separate colonoscopies within 12 months. I don't have a good answer for that insurance issue, but I would like you to understand that if the prep is only fair, and you're concerned that you might have missed a polyp, bringing the patient back in 5 years after normal screening colonoscopy is doing a disservice to the patient since the majority of interval cancers occurs within 3 and a half years of the index colonoscopy in those patients. If they've had 1 or 2 small adenomas, the vast majority of those patients have interval cancer within 24 months.