Risk Stratification Of Colorectal Polyps For Predicting Residual Or Recurring Adenoma Using The Size/Morphology/Site/Access Score

Background and Aims: Endoscopic mucosal resection is an effective and safe procedure to manage large non-pedunculated colonic polyps for which residual/recurrent adenoma is the main drawback. Size/Morphology/Site/Access score determines polypectomy difficulty. We aimed to describe residual/recurrent adenoma rate according to Size/Morphology/Site/Access and to select the ize/Morphology/Site/Access cut-off to predict low residual/recurrent adenoma.Methods: This was a retrospective cohort study of endoscopic mucosal resection for large non-pedunculated colonic polyps performed in a tertiary centre.Results: Three hundred and sixteen procedures were included. The mean size of lesions was 34.5 +/- 17.1mm, 59.5% were sessile, 60.4% were in the right colon and in 17.7% (n=56) the access was difficult. Of the lesions, 83.6% were Size/Morphology/Site/Access 3-4. Residual/recurrent adenoma at first and second follow-up was significantly lower in Size/Morphology/Site/Access 2 (1.9% and 0.0%, respectively) when compared to Size/Morphology/Site/Access 3 (18.2%, p=0.004 and 6.7%, p=0.049) and Size/Morphology/Site/Access 4 (30.8%, p<0.001 and 22.7%, p=0.030). The negative predictive value of Size/Morphology/Site/Access 2 for residual/recurrent adenoma at second follow-up was 86.1%. On multivariate analyses, Size/Morphology/Site/Access 3-4 predicted residual/recurrent adenoma at first (odds ratio 11.96, 95% confidence interval 1.57-91.13) and second follow-up (odds ratio 2.47, 95% confidence interval 1.51-4.22) and had higher cumulative incidence of residual/recurrent adenoma compared to Size/Morphology/Site/Access 2 (p <= 0.003).Conclusion: Use of the Size/Morphology/Site/Access score allows cases to be identified with a low risk of residual/recurrent adenoma.