Sessile Serrated Adenomas in the Proximal Colon are Likely to be Flat, Large and Occur in Smokers

Abstract

Purpose: Sessile serrated adenomas (SSA) have been implicated in the alternative pathway for colorectal carcinoma (CRC) and might account for interval CRC given the fact that these are often flat and difficult to detect. Most of the studies have focused on the relatively common left-sided serrated polyps and little is known about the proximal SSA. Our goal was to examine the epidemiology and morphology of proximal SSA. Methods: We conducted a retrospective study to identify patients with SSA using a pathology database query from 01/2007-04/2011. Data collected included: age, gender, ethnicity, BMI, diabetes, smoking, family history of CRC, aspirin, and statin use. We collected data on morphology of SSA including site (proximal or distal), size, and endoscopic appearance (flat or protuberant). SPSS software was used for all statistical analysis. P value <0.05 was considered significant. Results: 120 patients with SSA were identified: 61% were distal and 39% were proximal SSA. 78% of the distal SSA were flat compared to the proximal SSA which were all flat (p=0.0001). Proximal SSA were more likely to occur in smokers compared to distal (OR: 2.63; 95% CI: 1.17-5.90; p=0.02; Table 1). Similarly, smokers were more likely to have proximal (p=0.02) and flat (p=0.01) SSA compared to non-smokers. Proximal SSA were also more likely to occur in patients with family history of CRC (OR: 4.72; 95% CI: 1.43-15.55; p=0.01; Table 1). Proximal SSA were more likely to be ≥6 mm in size (OR: 2.94; 95% CI: 1.37-6.31; p=0.008), and also more likely to be large (≥1 cm) SSA (OR: 4.55; 95% CI: 1.92-10.77; p=0.0005) compared to the distal lesions as shown in Table 2.Table 1: No Caption available.Table: [1996] Table 2Conclusion: Proximal SSA which accounted for two-fifths of all SSA were more likely to present as flat lesions, larger SSA, and were more likely to occur in smokers and in patients with family history of CRC. Our study is the first to our knowledge examining morphology of SSAs specifically, and its association with smoking. Given the potential for malignancy of SSAs as well as their proclivity to a flat morphology, these lesions may explain the lack of protection of colonoscopy in the proximal colon. Our data has implications for CRC screening.