New research sheds light on ongoing bowel cancer surveillance needs

An Imperial-led study could help shape international colonoscopy guidelines, potentially easing pressure on healthcare systems and patients.

A new study from Imperial’s Department of Surgery and Cancer has provided crucial insights into who needs ongoing monitoring for bowel cancer by colonoscopy after initial polyp removal (known as ‘post-polypectomy surveillance’) - findings that could refine global bowel cancer surveillance practices.

“These findings could reduce the number of unnecessary colonoscopies, lessening the burden on healthcare systems and sparing patients from invasive procedures they may not need.” Professor Amanda Cross Department of Surgery and Cancer

Published in GUT, the study titled “Colorectal cancer incidence after the first surveillance colonoscopy and the need for ongoing surveillance: a retrospective, cohort analysis” was led by Imperial’s Cancer Screening and Prevention Research Group. The research addresses a major evidence gap in bowel cancer prevention, namely, which patients need to continue having post-polypectomy surveillance beyond their first surveillance colonoscopy.

Bowel cancer develops from polyps - small growths in the bowel that can turn cancerous over time. While removing polyps via colonoscopy significantly reduces bowel cancer risk, current guidance varies internationally on how long patients should continue to undergo post-polypectomy surveillance.

“For people entering post-polypectomy surveillance, there is a lack of data to identify those needing a second surveillance colonoscopy,” said first author, Miss Emma Robbins. “This study provides much-needed evidence on this topic, which will be valuable in informing recommendations for ongoing post-polypectomy surveillance in future iterations of the UK, European, and US post-polypectomy surveillance guidelines.”

The research team analysed data from over 10,500 patients and found that:

1. Patients with high-risk polyp findings at both their initial (baseline) and first surveillance colonoscopy had a significantly higher risk of developing bowel cancer than the general population. The researchers report that these patients should have a second surveillance colonoscopy.
2. Patients with low-risk findings at their first surveillance colonoscopy - regardless of whether they had low-risk or high-risk findings at their baseline colonoscopy  - were not at increased risk of bowel cancer compared to the general population. The researchers report that these patients can safely return to routine non-invasive bowel cancer screening, avoiding unnecessary further colonoscopies.

Impact on guidelines and patient care

The findings strongly support the 2020 UK post-polypectomy surveillance guidelines, which recommend stopping surveillance in patients with low-risk findings at the first surveillance colonoscopy. However, the study challenges more conservative approaches in the current European post-polypectomy surveillance guidelines, which recommend that patients continue surveillance until they have two consecutive surveillance colonoscopies at which low-risk findings are detected.

Speaking about the findings, Professor Amanda Cross, Professor of Cancer Epidemiology and last author, said: “These findings could reduce the number of unnecessary colonoscopies, lessening the burden on healthcare systems and sparing patients from invasive procedures they may not need.”

For patients, the study provides reassurance. Those with low-risk findings at their first surveillance colonoscopy, even if they had high-risk findings at their baseline colonoscopy, can be reassured that they are not at increased risk and can safely return to standard bowel cancer screening protocols.

Next steps

While the findings are promising, the authors note that the study’s ability to assess long-term surveillance needs in certain high-risk subgroups was limited by a small number of cancer cases. They suggest that future studies drawing on data from national screening programmes would help further refine recommendations.

The study not only supports current UK policy but offers a case for revisiting surveillance recommendations elsewhere in the world—potentially leading to a more evidence-based approach to bowel cancer prevention.

Colorectal cancer incidence after the first surveillance colonoscopy and the need for ongoing surveillance: a retrospective, cohort analysis.
Emma C Robbins, Kate Wooldrage Andrew M Veitch, Amanda J Cross. Gut Published Online First: 05 April 2025. doi: 10.1136/gutjnl-2024-334242 

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