Brits Evaluate Their New Postpolypectomy Surveillance Guidelines

Brits Evaluate Their New Postpolypectomy Surveillance Guidelines

Douglas K. Rex, MD, MASGE, reviewing Cross AJ, et al. Gut 2021 Mar 5.

The UK revised its postpolypectomy surveillance guidelines to reduce the use of surveillance colonoscopy. According to the guidelines, patients considered to be high risk for colorectal cancer (CRC) are those with:

  • ≥2 premalignant polyps (PMPs), of which ≥1 is advanced (adenoma ≥10 mm or with high-grade dysplasia, serrated polyp ≥10 mm or with dysplasia),
  • ≥5 PMPs, or
  • a single nonpedunculated lesion ≥20 mm. 

The guidelines recommend that high-risk patients undergo a single surveillance colonoscopy at 3 years and that everyone else with PMPs (low risk) does not need further surveillance colonoscopy but should instead return to screening (fecal occult blood test).

The 2020 guidelines were applied to patients who had undergone colonoscopy and polypectomy between 2000 and 2010 at 17 UK hospitals. Among 21,318 patients who had ≥1 conventional adenoma (serrated polyp data were not reliable during this interval) and a complete colonoscopy with good bowel preparation, 29% were considered high risk. 

Among low-risk patients without surveillance, CRC incidence at 10 years was 1.6%, which represented a 25% reduction in CRC risk compared to the general population. Any surveillance examination in the low-risk group was associated with a significant 42% reduction in CRC risk. 

Among high-risk patients without surveillance, 10-year CRC incidence was 3.3%, with a standardized incidence ratio of 1.30 compared to the general population. Any surveillance reduced CRC risk in the high-risk group by 29%, though the difference did not reach significance. 

Increased CRC risk was associated with older age, villous components, high-grade dysplasia, proximal polyp location, larger polyp size, and large numbers of polyps. 

The authors concluded that this study supports the British guidelines since CRC risk with no surveillance in the low-risk cohort was lower than that in the general population. CRC risk was higher in the high-risk group, and that risk was lowered to a level statistically within the general population risk by 1 surveillance colonoscopy.

Douglas K. Rex, MD, FASGE


U.S. interpretation of these data may differ. First, whether the general population is the right comparative group is debatable because the general population risk is substantial. Second, the reduction in risk without surveillance in the low-risk group compared to the general population was only 25%, a reduction rate that low-risk patients (and their lawyers) may not view as adequate. One surveillance examination in the low-risk group was associated with a 42% reduction in risk. This is consistent with a recent analysis of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial in the U.S., which suggested that surveillance colonoscopy in low-risk patients contributed to reduced CRC incidence and mortality. The same arguments apply to the high-risk population. Namely, is the goal to lower risk in the high-risk group to only the general population risk, or is it to eradicate their risk by effective clearing and surveillance? I consider the latter to be the goal.

Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.


Cross AJ, Robbins EC, Pack K, et al. Colorectal cancer risk following polypectomy in a multicentre, retrospective, cohort study: an evaluation of the 2020 UK post-polypectomy surveillance guidelines. Gut 2021 Mar 5. (Epub ahead of print) (

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