S0294 Smaller Sized Sessile Serrated Lesions in Asians Suggest the Need for a More Careful Examination of the Proximal Colon in This Population

Abstract

INTRODUCTION: Sessile serrated lesions (SSLs) are premalignant colonic lesions suspected to be a major cause of de-novo, colorectal cancers (CRCs) developing between screening colonoscopies. Studies have suggested an overall lower incidence of CRCs but a higher rate of de-novo CRCs in Asians, raising suspicion that SSLs may have a significant role in this population. However, prevalence and characteristics of SSLs in Asians undergoing CRC screening are seldom reported. METHODS: We conducted a retrospective review of index colonoscopy cases spanning 2017–2019 for patients age 50–59 years undergoing average-risk CRC screening at our urban tertiary care center. Data was collected for baseline patient characteristics, as well assize, location and histology of colonic lesions. Patients with personal or first-degree family history of CRC or premalignant lesions, hereditary CRC syndromes, inflammatory bowel disease, or poor bowel preparations were excluded. Statistical comparisons were performed using Student’s t-test, Chi-square test, and Fisher’s test. Logistic regression was performed to analyze the association between the development of SSLs and clinical variables. RESULTS: A total of 1100 patients consisting of Asians (N = 322, 29.3%) and non-Asians (N = 778, 70.7%) were included in the analysis Asians had lower prevalence of obesity, tobacco smoking, alcohol use, HIV infection, and distant family history of CRC when compared to non-Asians (Table 1). The overall prevalence of SSLs (8.1%) was similar to prior studies, and between Asians and non-Asians (6.8% and 8.6% respectively, P = 0.33). The mean SSL size was significantly smaller in Asians (4.7 ± 2.4 mm vs. 7.3 ± 5.7 mm, P = 0.001). Most SSLs were located proximal to the splenic flexure in both groups (75.0% in Asians and 84.1% in non-Asians, P = 0.35). Only tobacco smoking was independently associated with the development of SSLs (Table 2). CONCLUSION: We found that SSLs are as prevalent and smaller in size on index screening colonoscopy among average-risk Asians compared to the general population. Due to their flat appearance and proximal location, SSLs are more difficult to identify endoscopically. In addition, smaller lesions are more likely to be missed on routine screening colonoscopy. This suggests the need for more thorough inspection of the proximal colon during index screening of this population, along with more frequent screening, mirroring some of the recently evolving guidelines for other specific patient populations.Table 1.: Baseline characteristics of the patient populationTable 2.: Univariate and multivariate models demonstrating the association between the outcome of sessile serrated lesions and clinical variables in the entire cohort (N = 1,100)