WASHINGTON—Gastroenterology providers are getting used to the latest recommended intervals for colon cancer surveillance after polypectomy, but areas of confusion and a high degree of nonadherence remain.
“We have to do a better job of getting that discordance rectified in practice,” according to Rajesh N. Keswani, MD, MS, the director of endoscopy at Northwestern Memorial Hospital and the director of quality for the Digestive Health Center at Northwestern Medicine, in Chicago.
At DDW 2024, Dr. Keswani described some areas of misconceptions and offered some recommendations on colonoscopy intervals. The seven recommendations he listed, five of which focus on scenarios of different polyp types and sizes, all assume that a high-quality colonoscopy was done and follow the latest update from the U.S. Multi-Society Task Force on Colorectal Cancer (USMSTF; Gastroenterology 2020;158[4]:1131-1152.e5).
One or Two 6-mm Adenomas
The recommendation for patients with one to two tubular adenomas smaller than 10 mm that are removed completely is to repeat the colonoscopy in seven to 10 years (USMSTF strong recommendation). “This patient’s risk of having a significant polyp on future colonoscopies is about the same (4.9%) as someone with a normal colonoscopy (3.3%) [Am J Gastroenterol 2017;112(12):1790-1801],” said Dr. Keswani, an associate professor of medicine at Northwestern University Feinberg School of Medicine. “You can extend this interval to 10 years, but my disclosure is that I bring this patient back in seven years. You do have the flexibility, supported by data, to go to 10 years, especially if you are a high-quality colonoscopist.”
Three Sub-Centimeter Adenomas
The recommendation for patients with three to four adenomas smaller than 10 mm that are removed completely is to repeat colonoscopy in three to five years (USMSTF weak recommendation). The change from previous guidelines is splitting three to four polyps from five to 10 polyps. Multiple studies have shown lower rates of metachronous advanced lesions in patients with three to four (<2%) versus five to 10 (5%) sub-centimeter adenomas (Gastrointest Endosc 2014;80[2]:299-306).
Single 1.5-cm Adenoma Removed En Bloc
For one or more adenomas at least 10 mm in size that are removed completely, guidelines say to repeat colonoscopy in three years (USMSTF strong recommendation). “The caveat is that we, as endoscopists ... do a poor job of measuring polyps [Endoscopy 2024;56(6):421-430]. … We have too many polyps that are measured as 10 mm or greater. This is an area where AI could be helpful,” he said. The USMSTF acknowledged the importance of accurate estimates and suggested photo-documentation to verify polyp size relative to an open forceps or open snare of known size.
Single 1.5-cm Adenoma Removed Piecemeal
For patients with piecemeal resection of adenomas or sessile serrated polyps larger than 20 mm, the recommendation is to repeat colonoscopy in six months (USMSTF strong recommendation). The rationale is that the recurrence rate after piecemeal resection is much higher (20%) than after en bloc resection (3%), and the rate is high whether the polyp is 10 to 19 mm (18%) or larger than 20 mm (19%) (Endoscopy 2014;46[5]:388-402). “I would personally argue if you remove a polyp piecemeal that is larger than 10 mm, you bring that patient back early rather than wait three years because the risks of residual polyp are so high” with piecemeal polypectomy, Dr. Keswani said.
He noted that the effectiveness of polypectomy varies by clinician, and recurrences after piecemeal resection are not rare. In one study in which five endoscopists removed 346 polyps, 10% of polyps overall were resected incompletely, with rates of incomplete resection varying from 6.5% to 22.7% (Gastroenterology 2013;144[1]:74-80.e1).
Two 6-mm Sessile Serrated Polyps
For patients with one to two sessile serrated polyps that are smaller than 10 mm and removed completely, Dr. Keswani recommends repeat colonoscopy in five to 10 years (USMSTF weak recommendation). These patients are at low risk for a future high-risk adenoma, although they have an elevated risk for advanced serrated lesions.
“The biggest blind spot is that we are ultra-focused on the colonoscopy we are doing now,” he said. “We need to keep in mind that these patients have a history—maybe do some math and figure out whether the patient may have sessile serrated polyposis syndrome,” based on cumulative polyp burden.
The WHO criteria state that the presence of at least five serrated polyps proximal to the rectum, all being at least 5 mm and two being at least 10 mm, indicates sessile serrated polyposis syndrome. Alternatively, there can be more than 20 serrated polyps of any size throughout the colon, with at least five being proximal to the rectum.
“I think of it this way,” Dr. Keswani said. “Once I get to two polyps that are serrated and greater than 1 cm, I know there are probably other small, serrated ones that I’ve removed. … Once we’ve identified them, the goal is to remove them on index colonoscopy. But there may be so many that we can’t remove them all, so we bring these patients back at a shockingly frequent interval—sooner than one year, and then every one to two years.” Noting tht he considers “a one-year interval mostly for patients at highest risk,” he said, “The worry is you missed an advanced lesion, and if my gut tells me this, I bring the patient back earlier.”
Interpreting Pathology Results
Dr. Keswani cautioned against relying completely on pathology results. “It’s important to understand that the gold standard is not perfect,” he said. There are cases, for example, in which pathology labels a 6-mm polyp as “normal colon mucosa,” but Dr. Keswani feels it could be otherwise. “In my personal practice, where I am confident I’ve taken an adenoma but also a large bit of tissue, rather than go back to the pathologist to discuss it, I will treat it as an adenoma.”
Scheduling Colonoscopies Too Soon
Nonadherence to the guidelines remains a problem, Dr. Keswani noted. Endoscopists may know the guidelines but still choose to act differently, mostly deviating by scheduling future colonoscopies sooner than necessary.
Why? There are several different reasons, he explained. A clinician could worry that the patient has risk factors not addressed by the guidelines, such as a second-degree relative with colon cancer, or they may fear a missed adenoma—and the potential for litigation, he said. Others may question the strength of the underlying evidence, or “most concerningly,” he said, “they may have financial disincentives to stretch the interval.”
As an example, “I remember a patient who told me, ‘My doctor had me come back every year because he really cared about me,’” he said.
Dr. Keswani suggested that adherence to surveillance guidelines might be improved through better education, use of automated surveillance calculators and the availability of guidelines at the point of care. “At Northwestern Medicine, we have a hyperlink that allows us to go straight to the interpretive version of the guidelines,” he said, and a quick summary of the guidelines hangs in the endoscopy unit.
—Caroline Helwick
Dr. Keswani reported no relevant financial disclosures.
This article is from the November 2024 print issue.