The absolute number of high-grade dysplasia (HGD) is substantially higher from micro-polyps compared to that from larger size polyps, a retrospective pooled study

Abstract Importance: The risk that a large polyp (≥10mm) develops into high-grade dysplasia (HGD) is relatively high compared to that of a micro polyp (<10mm). Recently, the detection of micro polyps has been substantially improved with the advancement of endoscopy. However, the incidence of HGD caused by the combined number of micro polyps in the progression of HGD remains to be clarified. Objective: In this study, we aim to investigate whether and how the micro and diminutive polyps correlate with the incidents of HGD in population. Evidence Review: The pooled data were deeply analyzed from four published randomized controlled trials (RCTs) regarding colon polyp detection. HGD was confirmed through histopathology. The primary outcome was the correlation between the size of detected polyps with the confirmed HGD incident rate. Findings: Among a total of 3,179 patients with 2,730 polyps identified, there were 83 HGD polyps confirmed, and 68 patients had at least one polyp with HGD. The risk of development of HGD was lower for a single micro-polyp compared to that for one large polyp (2.18% vs 22.22%, p<0.0001). On the contrary, the constitutional ratio for HGD from micro polyps was significantly higher than that from the large ones (68.67% vs 31.33%, p<0.0001). Furthermore, the total number of micro polyps per patient was positively correlated to the total number of HGD (p<0.0001). The combined number of HGD presented a trend to be negatively correlated to its size. Conclusions: Our data demonstrated that the absolute number of HGD significantly derives more from micro polyps than that from the large ones, and the collective number of micro polyps per patient is indicative of his/her HGD exposure. These findings positively provide novel perspectives on the management of polyps, and further may optimize the prevention of colorectal cancer.