Effect of Diminutive Adenoma with High-Grade Dysplasia on Surveillance Colonoscopy Interval

Abstract

Background Colonoscopy surveillance guidelines set the surveillance schedule based on polyp characteristics. Polyps with high-grade dysplasia (HGD) require 3 years of follow-up regardless of size. However, it is unclear whether patients with diminutive polyps (≤5 mm) with HGD have a higher risk. We evaluated the effect of diminutive adenoma with HGD on adenoma occurrence. Methods From Jan 2015 to Dec 2017, patients who underwent index and surveillance colonoscopy were retrospectively screened. The patients were grouped into no adenoma group, low-risk (patients with ≤2 low-grade dysplasia (LGD)), diminutive HGD and high-risk (HGD >5 mm, ≥3 adenomas) groups according to the index colonoscopy results. Each group was analyzed using logistic analysis. Results The mean follow-up period was 22.47 months. Altogether, 610 (50.45%) patients had LGD and 152 (12.5%) had HGD. Among them, 61(5.0%) patients had a diminutive polyp with HGD. Analysis of the risks of developing advanced adenoma in the surveillance colonoscopy showed that compared to no adenoma group, the diminutive HGD group did not show a significant risk (odds ratio [OR]=1.503 [0.449–5.027], p=0.509), while the high-risk group showed a significant risk (odds ratio [OR]=2.044 [1.015–4.114], p=0.045). Conclusions Diminutive adenoma with HGD increased the risk of adenoma on surveillance colonoscopy, In the case of advanced adenoma, the risk was increased, but it was not statistically significant.

Large serrated polyps indicate a greater risk of advanced metachronous colorectal neoplasia than high-grade adenomas

“…It found the diminutive HGD group to have a similar risk of future AA as the 1-2 low-grade dysplastic adenoma group. [21] In our study, we found HGD in the context of 1-2 small TAs at index for 14 of 155 patients (9.0%). Four of the 14 patients developed TMAN during follow-up (3 AN and 1 ASL), all at later than 5 years of followup.…”

“…A recent study compared 61 patients with diminutive HGD (≤ 5 mm) with patients with one to two low-grade dysplastic adenomas. It found the diminutive HGD group to have a similar risk of future AA as the one to two low-grade dysplastic adenoma group 28 . In our study, we found HGD in the context of one to two small TAs at index for 14 of 155 patients (9.0%).…”

The absolute number of small and diminutive adenomas with high-grade dysplasia is substantially higher compared with large adenomas: a retrospective pooled study

“…Consequently, those polyps missed or untreated at the screening colonoscopy may be the cause of interval cancers, which account for approximately 8.2% of all CRC cases ( 1 ). In addition, patients whose polyps were removed during the screening colonoscopy but not pathologically evaluated have been advised a prolonged surveillance interval due to the unawareness of any possible HGD, which may also be the source of interval cancers due to the occurrence of metachronous advanced neoplasia during the prolonged surveillance interval ( 37 – 41 ). Our results might partially explain the interval CRC incidence in those days when small and diminutive polyps could not be effectively identified or treated.…”