Serrated Polyps and Risk of Advanced Colorectal Neoplasia
The study population comprised 4989 subjects. Among these individuals, 47% were men. The median age was 58-year old. The distribution of the subjects among each age category was as follows: 34% in the age group <55 years, 28% in 56–59 years, 27% in 60–65 years, 10% in 66–70 years, and 1% in >70 years old. The caecal intubation rate was 99.5%, and the median withdrawal time for colonoscopy was 7.83 min (Interquartile range, 6.22–11.58). Bowel preparation was excellent in 698 (14.0%), good in 2804 (56.2%) and fair in 1469 (29.4%). Subjects with poor bowel preparation were excluded.
Among the studied population, 281 (5.7%) had advanced neoplasia and were identified as cases. These included 23 (0.5%) subjects with invasive adenocarcinoma, 49 (1.0%) with high-grade dysplasia, 139 (2.8%) with villous or tubulovillous adenoma and 212 (4.2%) with tubular adenoma ≥1 cm in size. About 4708 subjects did not have advanced neoplasia and were referred to as controls, of which 3401 subjects had no adenomas. The characteristics of the cases and controls are shown in Table 1.
Serrated polyps were found in 279 (5.6%) of the subjects including 221 (4.4%) with hyperplastic polyps (those with small distal hyperplastic polyps were excluded), 60 (1.2%) with sessile serrated adenomas, and 2 (0.04%) with traditional serrated adenomas. In total, 194 subjects (3.9%) had large or proximal serrated polyps in the colorectum. Large and proximal serrated polys were identified in 19 (0.4%) and 183 (3.7%) subjects respectively. The average number of serrated polyps per patient was 1.25 (±0.60), (range, 1–5); 226 (4.5%) and 41 (0.8%) subjects had one and two serrated polyps respectively.
In univariate analysis, advanced neoplasia was associated with increasing age (odds ratio (OR): 1.85; 95% CI, 1.45–2.37 for subjects 60–69 years old, OR: 3.45; 95% CI: 1.87–6.34 for subjects 70–79 years old), male gender (OR: 1.84; 95% CI: 1.44–2.35), smoking history (OR: 2.05; 95% CI: 1.41–2.97), a family history of CRC (OR: 1.47; 95% CI: 1.08–2.00) and serrated polyps (OR: 2.80; 95% CI: 1.94–4.05). Cases with advanced neoplasia had a higher BMI than those without advanced neoplasia (P < 0.001). Synchronous advanced neoplasia were more commonly found in individuals with hyperplastic polyps (OR: 1.93; 95% CI: 1.22–3.04), sessile serrated adenomas (OR: 5.31; 95% CI: 2.86–9.79), proximal serrated polyps (OR: 2.40, 95% CI: 1.51–3.81), large serrated polyps (OR: 66.32; 95% CI: 21.86–201.19) and three or more serrated polyps (OR: 5.63; 95% CI: 1.52–20.93). Synchronous advanced neoplasia was also associated with increasing number of non-advanced adenomas (OR: 4.05; 95% CI: 3.02–5.43 for one adenoma, OR: 8.47; 95% CI: 6.09–11.79 for two adenomas; OR: 15.37; 95% CI: 10.96–21.56 for three or more adenomas; Table 2). There was no significant association between large hyperplastic polyps and the risk of synchronous advanced neoplasia. However, proximal hyperplastic polyps (OR: 1.87; 95% CI: 1.10–3.19) were also associated with synchronous advanced neoplasia.
In multivariate analysis after adjusting for age, gender, smoking history, BMI and a family history of CRC, independent predictors of synchronous advanced colorectal neoplasia were the presence of hyperplastic polyps (OR: 1.66; 95% CI: 1.03–2.67; excluding small distal hyperplastic polyps), sessile serrated adenomas (OR: 4.52; 95% CI: 2.40–8.49), proximal serrated polyps (OR: 2.23, 95% CI: 1.38–3.60), large serrated polyps (OR: 59.25; 95% CI: 18.85–186.21), three or more serrated polyps (OR: 4.86; 95% CI: 1.24–19.15) and one or more nonadvanced tubular adenomas (OR: 3.58, 95% CI: 2.59–4.96; Table 2).
Subjects with proximal serrated polyps had a higher risk of having ≥3 nonadvanced tubular adenomas compared with those with no proximal serrated polyps (OR: 1.99; 95% CI: 1.23–3.24). Subjects with proximal serrated polyps also had a higher risk of ≥3 serrated polyps (OR: 16.16; 95% CI: 10.94–23.88). In addition, those with large serrated polyps were more likely to have multiple serrated polyps than were those without large serrated polyps (OR: 9.38; 95% CI: 3.16–27.85).
Hyperplastic polyps were more prevalent than the other types of serrated polyps. Among 279 subjects with serrated polyps, 221 patients (4.4) had at least one hyperplastic polyp (after exclusion of small distal hyperplastic polyps) and 62 (1.2%) had at least one nonhyperplastic serrated polyp (SSA or TSA). Large lesions (≥10 mm) were detected in 2.7% and 22.6% of the hyperplastic and nonhyperplastic serrated lesions, respectively (P < 0.001). 74.2% and 35.5% of the hyperplastic and nonhyperplastic serrated polyps, respectively, were located in the proximal colon (P < 0.001). We found that the presence of proximal hyperplastic polyps was associated with advanced colorectal neoplasia (OR: 1.87; 95% CI: 1.10–3.19).
Clinical and biological characteristics have been shown to be different between colorectal neoplasia in the proximal and distal colon. We investigated predictors of advanced neoplasia according to lesion location (Table 3). Male gender and BMI were associated with distal advanced neoplasia, whereas a family history of CRC was associated with proximal advanced neoplasia. The detection of proximal serrated polyps was more associated with proximal advanced neoplasia (OR: 9.74; 95% CI: 1.53–62.22) compared with distal advanced neoplasia (OR: 0.50; 95% CI: 0.18–1.36). The risk presented by the presence of sessile serrated adenomas and large serrated polyps was, however, not different for advanced neoplasia either in the proximal or distal colon (Table 3).
Results
The study population comprised 4989 subjects. Among these individuals, 47% were men. The median age was 58-year old. The distribution of the subjects among each age category was as follows: 34% in the age group <55 years, 28% in 56–59 years, 27% in 60–65 years, 10% in 66–70 years, and 1% in >70 years old. The caecal intubation rate was 99.5%, and the median withdrawal time for colonoscopy was 7.83 min (Interquartile range, 6.22–11.58). Bowel preparation was excellent in 698 (14.0%), good in 2804 (56.2%) and fair in 1469 (29.4%). Subjects with poor bowel preparation were excluded.
Among the studied population, 281 (5.7%) had advanced neoplasia and were identified as cases. These included 23 (0.5%) subjects with invasive adenocarcinoma, 49 (1.0%) with high-grade dysplasia, 139 (2.8%) with villous or tubulovillous adenoma and 212 (4.2%) with tubular adenoma ≥1 cm in size. About 4708 subjects did not have advanced neoplasia and were referred to as controls, of which 3401 subjects had no adenomas. The characteristics of the cases and controls are shown in Table 1.
Serrated polyps were found in 279 (5.6%) of the subjects including 221 (4.4%) with hyperplastic polyps (those with small distal hyperplastic polyps were excluded), 60 (1.2%) with sessile serrated adenomas, and 2 (0.04%) with traditional serrated adenomas. In total, 194 subjects (3.9%) had large or proximal serrated polyps in the colorectum. Large and proximal serrated polys were identified in 19 (0.4%) and 183 (3.7%) subjects respectively. The average number of serrated polyps per patient was 1.25 (±0.60), (range, 1–5); 226 (4.5%) and 41 (0.8%) subjects had one and two serrated polyps respectively.
Predictors of Advanced Colorectal Neoplasia
In univariate analysis, advanced neoplasia was associated with increasing age (odds ratio (OR): 1.85; 95% CI, 1.45–2.37 for subjects 60–69 years old, OR: 3.45; 95% CI: 1.87–6.34 for subjects 70–79 years old), male gender (OR: 1.84; 95% CI: 1.44–2.35), smoking history (OR: 2.05; 95% CI: 1.41–2.97), a family history of CRC (OR: 1.47; 95% CI: 1.08–2.00) and serrated polyps (OR: 2.80; 95% CI: 1.94–4.05). Cases with advanced neoplasia had a higher BMI than those without advanced neoplasia (P < 0.001). Synchronous advanced neoplasia were more commonly found in individuals with hyperplastic polyps (OR: 1.93; 95% CI: 1.22–3.04), sessile serrated adenomas (OR: 5.31; 95% CI: 2.86–9.79), proximal serrated polyps (OR: 2.40, 95% CI: 1.51–3.81), large serrated polyps (OR: 66.32; 95% CI: 21.86–201.19) and three or more serrated polyps (OR: 5.63; 95% CI: 1.52–20.93). Synchronous advanced neoplasia was also associated with increasing number of non-advanced adenomas (OR: 4.05; 95% CI: 3.02–5.43 for one adenoma, OR: 8.47; 95% CI: 6.09–11.79 for two adenomas; OR: 15.37; 95% CI: 10.96–21.56 for three or more adenomas; Table 2). There was no significant association between large hyperplastic polyps and the risk of synchronous advanced neoplasia. However, proximal hyperplastic polyps (OR: 1.87; 95% CI: 1.10–3.19) were also associated with synchronous advanced neoplasia.
In multivariate analysis after adjusting for age, gender, smoking history, BMI and a family history of CRC, independent predictors of synchronous advanced colorectal neoplasia were the presence of hyperplastic polyps (OR: 1.66; 95% CI: 1.03–2.67; excluding small distal hyperplastic polyps), sessile serrated adenomas (OR: 4.52; 95% CI: 2.40–8.49), proximal serrated polyps (OR: 2.23, 95% CI: 1.38–3.60), large serrated polyps (OR: 59.25; 95% CI: 18.85–186.21), three or more serrated polyps (OR: 4.86; 95% CI: 1.24–19.15) and one or more nonadvanced tubular adenomas (OR: 3.58, 95% CI: 2.59–4.96; Table 2).
Subjects with proximal serrated polyps had a higher risk of having ≥3 nonadvanced tubular adenomas compared with those with no proximal serrated polyps (OR: 1.99; 95% CI: 1.23–3.24). Subjects with proximal serrated polyps also had a higher risk of ≥3 serrated polyps (OR: 16.16; 95% CI: 10.94–23.88). In addition, those with large serrated polyps were more likely to have multiple serrated polyps than were those without large serrated polyps (OR: 9.38; 95% CI: 3.16–27.85).
Predictors of Advanced Colorectal Neoplasia in Patients With Hyperplastic Polyps
Hyperplastic polyps were more prevalent than the other types of serrated polyps. Among 279 subjects with serrated polyps, 221 patients (4.4) had at least one hyperplastic polyp (after exclusion of small distal hyperplastic polyps) and 62 (1.2%) had at least one nonhyperplastic serrated polyp (SSA or TSA). Large lesions (≥10 mm) were detected in 2.7% and 22.6% of the hyperplastic and nonhyperplastic serrated lesions, respectively (P < 0.001). 74.2% and 35.5% of the hyperplastic and nonhyperplastic serrated polyps, respectively, were located in the proximal colon (P < 0.001). We found that the presence of proximal hyperplastic polyps was associated with advanced colorectal neoplasia (OR: 1.87; 95% CI: 1.10–3.19).
Association Between Serrated Polyps and Synchronous Advanced Colorectal Neoplasia Based on Location
Clinical and biological characteristics have been shown to be different between colorectal neoplasia in the proximal and distal colon. We investigated predictors of advanced neoplasia according to lesion location (Table 3). Male gender and BMI were associated with distal advanced neoplasia, whereas a family history of CRC was associated with proximal advanced neoplasia. The detection of proximal serrated polyps was more associated with proximal advanced neoplasia (OR: 9.74; 95% CI: 1.53–62.22) compared with distal advanced neoplasia (OR: 0.50; 95% CI: 0.18–1.36). The risk presented by the presence of sessile serrated adenomas and large serrated polyps was, however, not different for advanced neoplasia either in the proximal or distal colon (Table 3).
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