Objective Postpolypectomy colonoscopy surveillance aims to prevent colorectal cancer (CRC). The 2002 UK surveillance guidelines define low-risk, intermediate-risk and high-risk groups, recommending different strategies for each. Evidence supporting the guidelines is limited. We examined CRC incidence and effects of surveillance on incidence among each risk group.
Design Retrospective study of 33 011 patients who underwent colonoscopy with adenoma removal at 17 UK hospitals, mostly (87%) from 2000 to 2010. Patients were followed up through 2016. Cox regression with time-varying covariates was used to estimate effects of surveillance on CRC incidence adjusted for patient, procedural and polyp characteristics. Standardised incidence ratios (SIRs) compared incidence with that in the general population.
Results After exclusions, 28 972 patients were available for analysis; 14 401 (50%) were classed as low-risk, 11 852 (41%) as intermediate-risk and 2719 (9%) as high-risk. Median follow-up was 9.3 years. In the low-risk, intermediate-risk and high-risk groups, CRC incidence per 100 000 person-years was 140 (95% CI 122 to 162), 221 (195 to 251) and 366 (295 to 453), respectively. CRC incidence was 40%–50% lower with a single surveillance visit than with none: hazard ratios (HRs) were 0.56 (95% CI 0.39 to 0.80), 0.59 (0.43 to 0.81) and 0.49 (0.29 to 0.82) in the low-risk, intermediate-risk and high-risk groups, respectively. Compared with the general population, CRC incidence without surveillance was similar among low-risk (SIR 0.86, 95% CI 0.73 to 1.02) and intermediate-risk (1.16, 0.97 to 1.37) patients, but higher among high-risk patients (1.91, 1.39 to 2.56).
Conclusion Postpolypectomy surveillance reduces CRC risk. However, even without surveillance, CRC risk in some low-risk and intermediate-risk patients is no higher than in the general population. These patients could be managed by screening rather than surveillance.
- colorectal cancer
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Contributors AJC and KW were responsible for study design. PLK was responsible for study management. IS, KP and BP were responsible for data acquisition and coding. AJC, KW and SWD were responsible for oversight of data analysis. KW did the statistical analyses. AJC, KW and ECR interpreted the data. ECR wrote the first draft of the manuscript. AMV, BPS and MDR critically evaluated the findings and provided clinical input. All authors critically appraised the final manuscript and gave final approval of the version to be published.
Funding This is a summary of independent research funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) programme (reference NIHR-HTA 15/80/13), the Bobby Moore Fund for Cancer Research UK (reference C8171/A16894), and the Cancer Research UK Population Research Committee Programme Award (reference C53889/A25004).
Disclaimer The funders had no role in the study design, data collection, analysis or interpretation, manuscript writing or decision to submit for publication. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, the Department of Health or Cancer Research UK. Infrastructure support for this work was provided by the NIHR Imperial Biomedical Research Centre.
Competing interests AJC, as Chief Investigator, was the recipient of all the funding. MDR reports personal fees from Swiss SCWeb AG, Pentax and Norgine, and a grant from Olympus, outside the submitted work.
Patient consent for publication Not required.
Ethics approval Ethics approval for the original study of the intermediate-risk group was granted by the Royal Free Research Ethics Committee (REC) (reference 06/Q0501/45). Further ethics approval was granted for the substantial amendments that extended the scope of the protocol to examine the low-risk and high-risk groups, in addition to the intermediate-risk group previously analysed, by the London – Hampstead REC and the Health Research Authority (HRA) (REC reference 06/Q0501/45, IRAS ID 55943). Approval for the processing of patient identifiable information without consent was originally granted by the Patient Information Advisory Group (PIAG) under Section 60 of the Health and Social Care Act 2001 (re-enacted by Section 251 of the NHS Act 2006) and subsequent amendments/annual reviews were approved by the HRA-Confidentiality Advisory Group (reference PIAG 1–05[e]/2006).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. We may be able to share de-identified participant data with researchers following publication of this manuscript. Requests for data should be directed to the corresponding author. Data sharing will need to be approved by third party data providers.
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