A UK retrospective study showed that colonoscopic surveillance was associated with a reduced risk of colorectal cancer among patients with removal of intermediate-risk adenomas. The study was reported in The Lancet Oncology by Atkin et al.
The study involved routine lower gastrointestinal endoscopy and pathology data from 11,944 patients from 17 hospitals who were diagnosed with intermediate-risk adenomas between January 1990 and December 2010 after baseline colonoscopy and polypectomy. Intermediate-risk adenomas were defined as one or two large (≥ 10 mm) adenomas or three or four small adenomas. Intermediate-risk patients currently are offered colonoscopy surveillance at 3-year intervals. Standardized incidence ratios for colorectal cancer were calculated using the general population of England in 2007 as the reference population.
Surveillance and Risk
After a median follow-up of 7.9 years, 210 colorectal cancers were diagnosed. A total of 5,019 patients (42%) did not undergo surveillance colonoscopy, and 6,925 patients (58%) attended at least one surveillance visit. Compared with patients with no surveillance, those with one (adjusted hazard ratio [HR] = 0.57, 95% confidence interval [CI] = 0.40–0.80) or two visits (adjusted HR = 0.51, 95% CI = 0.31–0.84) had a significantly reduced risk for colorectal cancer. A similar reduction in risk was observed for those with at least three visits (adjusted HR = 0.54, 95% CI = 0.29–0.99).
Among patients in a higher-risk subgroup defined by suboptimal-quality colonoscopy, proximal polyps, or a high-grade or large adenoma (≥ 20 mm) at baseline (8,865 patients, 74%), those with no surveillance visits had a significantly higher risk for colorectal cancer vs the general population (standardized incidence ratio = 1.30, 95% CI = 1.06–1.57). Among patients without these characteristics, those with no surveillance visits had risk for colorectal cancer lower than that in the general population (standardized incidence ratio = 0.51, 95% CI = 0.29–0.84).
The investigators concluded: “Colonoscopy 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.”
The study was funded by the National Institute for Health Research Health Technology Assessment, Cancer Research UK.
Wendy Atkin, PhD, of the Cancer Screening and Prevention Research Group, Imperial College London, is the corresponding author of The Lancet Oncology article.
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