Prevalence of diverse colorectal polyps and risk factors for colorectal carcinoma in situ and neoplastic polyps
Authors: Li Xiaojuan , Hu Mengting , Wang Zhangjun , Liu Mei , Chen Ying 
Published: September 2023

Purposes: Colorectal cancer, which accounts for 10.0% of all cancers worldwide and is the second leading cause of cancer death. The majority of colorectal cancer begins as precancerous polyps. This study aimed to determine the incidence of colorectal polyps with diverse pathological morphologies and to explore the risk factors of colorectal carcinoma in situ and neoplastic polyps.
Methods: Inpatients from January 2018 to May 2023 were screened through the inpatient electronic medical database. According to the pathological morphology of polyps, they were divided into hyperplastic polyps, inflammatory polyps, juvenile polyps, tubular adenoma, tubulovillous adenoma, serrated adenoma, and carcinoma in situ polyps. The incidence of polyps was described by percentage and odds ratio(OR). Univariate and multivariate logistic regression analyses were used to explore the risk factors of carcinoma in situ and neoplastic polyps.
Results: In total, 2329 individuals with 3550 polyps were recruited, 64.92% were male, with a mean age of 60.38±12.08 years. Neoplastic polyps accounted for 76.99%, advanced adenomas for 44.31%, and multiple polyps for 48.65% of all patients with colorectal polyps. The incidence of various pathological polyps was 60.15% (95%CI 58.16%–62.14%) for tubular adenoma, 31.22% (95%CI 29.33%–33.10%) for hyperplastic polyps, 26.62% (95%CI 24.82%–28.42%) for inflammatory polyps, 26.02% (95%CI 24.24%–27.80%) for tubulovillous adenoma, 4.16% (95%CI 3.35%–4.98%) for serrated adenoma, 3.86% (95%CI 3.08%–4.65%) for carcinoma in situ, and 0.39%for juvenile polyps (95%CI 0.13%–0.64%).
Subsequently, we analyzed the risk factors of colorectal polyps in patients with carcinoma in situ and found that the number of polyps in patients with colorectal polyps ≥3, diameter ≥1.0cm, Schistosome egg deposition, CA724, CA211 were risk factors for colorectal carcinoma in situ. Colorectal polyps diameter ≥1.0cm were 8.07 times more likely to develop carcinoma in situ than those with a diameter <1.0cm, OR 8.07,95%CI 4.48–14.55, p<0.0001. Colorectal polyps ≥3 were 1.98 times more likely to develop carcinoma in situ than those with polyps <3, OR 1.98,95%CI 1.27–3.09, p=0.002. The risk of colorectal carcinoma in situ with Schistosome egg deposition was also significantly increased (OR 2.70,95%CI 1.05–6.98). The higher the levels of CA724 (OR 1.01,95%CI 1.00–1.02) and CA211 (OR 1.16,95%CI 1.03–1.32) in patients with colorectal polyps, the greater the risk of carcinoma in situ. When colorectal neoplastic polyps and non-neoplastic polyps were compared, it was discovered that for each 1-year rise in age, the risk of neoplastic polyps increased by 3% (OR1.03,95%CI 1.02–1.04), p<0.0001. Compared to colorectal polyp diameter <1.0cm, the risk of neoplastic polyps in patients with polyp diameter ≥1.0cm increased by 2.11 times (OR 3.11,95%CI 2.48–3.92), p<0.0001. In addition, multiple polyps and CA199 levels are risk factors for neoplastic polyps.
Conclusion: The pathological morphology of colorectal polyps was primarily tubular adenoma and tubulovillous adenoma, and more than 3/4 of them were neoplastic polyps, among which advanced adenoma contributed 44.31%. The prevalence of carcinoma in situ polyps in the population and polyps was, respectively, 3.86% and 2.54%. Patients are more inclined to develop colorectal carcinoma in situ and neoplastic polyps if they have large polyps (>1.0 cm) and multifocal polyps. The levels of the tumor markers CA724 and CA211 show some potential usefulness for predicting colorectal carcinoma in situ, which may be exploited for early identification of high-risk populations.