PTU-60 The prevalence of serrated polyps in a multi-ethnic society in the United Kingdom

Field: Medicine (Health Sciences)

Introduction

Leicestershire is the 16th most populous county in the United Kingdom. The estimated population is around 706,1551. It has a multi-ethnic diverse group where non-white comprises 15% of its population1. The majority of the non-white is South Asian.

Aim

We aim to assess the prevalence of serrated polyps, defined as hyperplastic polyp (HP), sessile serrated lesion (SSL), traditional serrated adenoma (TSA) or mixed polyp2, in this multi-ethnic group in patients attending for Bowel Cancer Screening (BCS) colonoscopy.

Methods

We carried out a retrospective observational study of all serrated lesions (SLs) over a two-year period between 1st May 2018 to 30th April 2020. Patients' demographic, polyp morphology & site were obtained from our Bowel Cancer Screening Programme (BCSP) database. The self-reported ethnic origin of all individuals was recorded. Non-serrated lesions (i.e tubular adenoma, tubulovillous adenoma and villous adenoma) were excluded from the study. For statistical analysis we used Pearson Chi-square, independent sample T-test and one-way analysis of variance were used as appropriate. P value of 0.05 was considered statistically significant. All analysis was conducted using SPSS version 26.

Results

Over a 2 year-period, 2264 screening/surveillance colonoscopies were carried out, of which 493 patients had one or more SLs. The mean age was 67.6 years, and 66.5% of patients were male. The white Caucasian comprised 87.2% (n=430) of the study population while the Asian group was 12.8% (n=63). The frequency of polyps as per morphology was as following: hyperplastic 82.4% (n=406), sessile serrated lesion 10.5% (n=52), traditional serrated lesion 1.2% (n=6) and mixed type 5.9% (n=29). In the white group: 80.2% (n=345) of polyps were hyperplastic, 11.7% (n=50) were SSL, 1.4% (n=6) was TSA and 6.7% (n=29) were mixed type. In the Asian group: 96.8% (n=61) of polyps were hyperplastic, 3.2% (n=2) were SSL and none was TSA or mixed type. The mean number of SLs per individual was significantly higher in white Caucasian than in Asians, 1.53 (SD 1.10) vs. 1.23 (SD 0.49), (p= 0.001). Between the two groups, the prevalence of SSL and the mixed type were higher in the white group (p= 0.001 and p=0.003, respectively). On the one-way analysis, the mixed type was more prevalent amongst the different types of SLs (p=0.001). The site of SLs in the colorectum, in order from highest to lowest, was as following: Sigmoid 53.6% (n=266), Rectum 25% (n=124), Ascending 23.5% (n=117), Transverse 20.9% (n=104), Caecum 11.4% (n=57), Descending 7% (n=35), Hepatic flexure 4.4% (n=22), Rectosigmoid 3.8% (n=19), Splenic flexure 2.6% (n=13), Ileocaecal valve 0.2% (n=1) and Appendicael orifice 0.2% (n=1).

Conclusions

The prevalence of SLs as well as the number of polyps per individual was higher in the white group compared to Asian and much higher in men. Nevertheless, the number of colonoscopies in the Asian group was much lower; therefore, this might not fully reflect the demographic differences between the two groups. SLs were higher in the left colon, particularly the sigmoid colon and were predominantly hyperplastic in nature. Between the two groups, the prevalence of SSL and mixed type polyp was higher and was more prevalent in the white group. Amongst the different types of SLs, the mixed type was more common.

References

https://en.wikipedia.org/wiki/Leicestershire. East JE, Atkin WS, Bateman AC, et al. British Society of Gastroenterology position statement on serrated polyps in the colon and rectum. Gut 2017;66:1181-1196.