10,000 Sessile Serrated Polyps: Slow Progression to Low-grade and Highgrade Dysplasia in a Large Nationwide Population: 2010 Presidential Poster

Abstract

Purpose: Sessile serrated polyps/adenomas (SSAs) are recognized precursors to microsatellite unstable adenocarcinomas. We have previously evaluated the prevalence of dysplasia and carcinoma arising in SSAs in a group of over 2,100 patients with SSAs (Lash, Schuler, Genta, J Clin Pathol, 2010). In this study we estimate the progression rate of SSAs based on the analysis of a much larger cohort. Methods: This study was conducted at Caris Life Sciences, a specialized gastrointestinal pathology laboratory receiving specimens from outpatient endoscopy centers across the U.S. We analyzed electronic data from the Caris database, which includes demographic, clinical, and endoscopic information, site of origin of each specimen, and the diagnostic report. From a series of over 515,724 patients who had a colonoscopy with mucosal biopsies from 1/2008 - 5/2010, we used computerized algorithms to extract data from all patients who had a histopathologic diagnosis of SSA, with or without low-grade (SSA-Low) and high-grade (SSA-High) dysplasia. Results: A total of 211,469 patients (41.0%) had non-hyperplastic epithelial polyps (56.9% men). 4.7% (10,064) of these patients had SSA, SSA-Low, or SSA-High. The most advanced polyp in these patients were: 9027 (89.7%) SSAs (median age 60 yrs, range 18-91; 53.6% women); 956 (9.5%) SSA-Low (median age 67 yrs, range 32-95; 58.9% women); and 81 (0.8%) SSA-High (median age 71 yrs, range 43-90; 67.9% women). The median age of women and men with SSA was similar (60 and 61, respectively). However, among patients with SSA-Low, women were 3 years older than men (68 versus 65, p<0.001) and among those with SSA-High, women were 5 years older than men (72 versus 67, p=0.006). In the same period, there were 203,359 patients with conventional adenomas with low-grade dysplasia (median age 63, 57.5% men) and 3437 with adenomas with high-grade dysplasia (median age 65, 58.1% men). Conclusion: This series confirms prior data showing SSAs are found in ˜1% of all colonoscopies and represent ˜5% of all non-hyperplastic colonic epithelial polyps. Based upon median age, these data suggest that the interval for the progression from SSA to SSA with low-grade dysplasia (˜10% of all those with SSAs) can be estimated to be approximately 7 years, and the further progression to high-grade dysplasia (˜9% of all those with SSAs) can be estimated at an additional 4 years. SSAs occur prevalently in women, who are also more prone to progress to dysplasia, albeit at an older age then men in our study. SSAs appear to advance at a slower rate than conventional adenomas.