Prevalence of Advanced Adenomas in Small and Diminutive Colon Polyps Using Direct Measurement of Size
Background and Aims
Most studies reporting polyp size use visual estimates. Determining the prevalence of advanced histology based on direct measurement of polyp size may help guide the management of polyps found at optical colonoscopy (OC) and CT colonography (CTC).
We designed a large, prospective study to assess the prevalence of advanced adenomas based on direct measurement of polyp size by a certified pathologists’ assistant as reported in the pathology report. Patients between 40 and 89 years of age who presented for screening colonoscopy were included in our study. Advanced adenomas were defined as ≥10 mm or ≥25% villous features, high grade dysplasia or cancer. Polyps were divided by size into three groups: diminutive (≤5 mm), small (6–9 mm) and large (≥10 mm). If more than one adenoma was present, the most advanced was used for analysis.
We evaluated 6,905 consecutive patients referred for colonoscopy between January 2005 and December 2006. Of the 4,967 who met the inclusion criteria, the mean age was 58.8 and consisted of 59% women. Overall, 930 (18.7%) had an adenoma; 248 (5%) were advanced adenomas including 8 (0.16%) cancers. Of 89 polyps ≥10 mm, 76 (85%) had advanced histology; of 247 polyps 6–9 mm, 67 (27%) were advanced; of 1,025 polyps ≤5 mm, 105 (10%) were advanced. Thus, 172 of 248 (69%) patients with advanced adenomas had small or diminutive adenomas.
Our data indicate the majority (69%) of advanced adenomas are <10 mm. Even among polyps ≤5 mm, there was an appreciable prevalence of advanced adenomas (10%). These findings may help guide the management of sub-centimeter colon polyps found by OC or CTC.
KeywordsAdvanced adenoma Polyp size Screening colonoscopy CT colonography
The authors are grateful for the diligent work of Irving C. Sandbakken, Karin Wheeler and Sharon Reid who assisted in collecting the data, Anne Feng and Dr James Koziol who provided expert statistical assistance, and our colleagues who performed the colonoscopic examinations. This study was supported by private donations to the Scripps Clinic Colorectal Cancer Research Study Program.
Conflict of interest
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