Adenoma surveillance and colorectal cancer incidence: a retrospective, multicentre, cohort study

Abstract

SummaryBackgroundRemoval of adenomas reduces colorectal cancer incidence and mortality; however, the benefit of surveillance colonoscopy on colorectal cancer risk remains unclear. We examined heterogeneity in colorectal cancer incidence in intermediate-risk patients and the effect of surveillance on colorectal cancer incidence.MethodsWe did this retrospective, multicentre, cohort study using routine lower gastrointestinal endoscopy and pathology data from patients who, after baseline colonoscopy and polypectomy, were diagnosed with intermediate-risk adenomas mostly (>99%) between Jan 1, 1990, and Dec 31, 2010, at 17 hospitals in the UK. These patients are currently offered surveillance colonoscopy at intervals of 3 years. Patients were followed up through to Dec 31, 2014.We assessed the effect of surveillance on colorectal cancer incidence using Cox regression with adjustment for patient, procedural, and polyp characteristics. We defined lower-risk and higher-risk subgroups on the basis of polyp and procedural characteristics identified as colorectal cancer risk factors. We estimated colorectal cancer incidence and standardised incidence ratios (SIRs) using as standard the general population of England in 2007. This trial is registered, number ISRCTN15213649.Findings253 798 patients who underwent colonic endoscopy were identified, of whom 11 944 with intermediate-risk adenomas were included in this analysis. After a median follow-up of 7·9 years (IQR 5·6–11·1), 210 colorectal cancers were diagnosed. 5019 (42%) patients did not attend surveillance and 6925 (58%) attended one or more surveillance visits. Compared to no surveillance, one or two surveillance visits were associated with a significant reduction in colorectal cancer incidence rate (adjusted hazard ratio 0·57, 95% CI 0·40–0·80 for one visit; 0·51, 0·31–0·84 for two visits). Without surveillance, colorectal cancer incidence in patients with a suboptimal quality colonoscopy, proximal polyps, or a high-grade or large adenoma (≥20 mm) at baseline (8865 [74%] patients) was significantly higher than in the general population (SIR 1·30, 95% CI 1·06–1·57). By contrast, in patients without these features, colorectal cancer incidence was lower than that of the general population (SIR 0·51, 95% CI 0·29–0·84).InterpretationColonoscopy surveillance benefits most patients with intermediate-risk adenomas. However, some patients are already at low risk after baseline colonoscopy and the value of surveillance for them is unclear.FundingNational Institute for Health Research Health Technology Assessment, Cancer Research UK.

Utilization and determinants of follow‐up colonoscopies within 6 years after screening colonoscopy: Prospective cohort study

“…According to studies on the risk of advanced neoplasms after polypectomy, the proportion of patients with advanced neoplasms would be expected to increase with longer intervals. A recent study reported strong variation of CRC risk in patients recommended to have surveillance colonoscopy after 3 years . Their finding that 3–4 smaller adenomas (<1 cm) at screening were not associated with higher CRC incidence during follow‐up challenges the 3‐year interval currently recommended for surveillance by German, United States and European guidelines.…”

The clinical effectiveness of different surveillance strategies to prevent colorectal cancer in people with intermediate-grade colorectal adenomas: a retrospective cohort analysis, and psychological and economic evaluations

“…For the hospital data, it was fairly straightforward to identify such cases: cancer outcomes were defined using specific cancer histology codes (codes 50,51,55,58,59,69). However, in order to determine which cancers from external sources were outcomes of interest, they all had to be grouped based on their morphology (Derived Morph Grouping derived from morphology codes) and site (Derived Site Grouping derived from site codes).…”

Colonoscopy quality requisites for selecting surveillance intervals: A World Endoscopy Organization Delphi Recommendation

“…Practice guidelines recommend post‐polypectomy surveillance intervals based on the estimated risk of metachronous neoplasia, which depends on the size, number, and histology of adenomas and serrated lesions found at baseline . However, adenoma and serrated polyp detection rates, as well as other quality standards, vary widely among endoscopists, highly influencing the chance of post‐colonoscopy cancers, maybe more than the advised interval …”