Literature reports on the prevalence of colorectal polyps vary greatly. This may be related to the study designs, the patient's socio-demographic characteristics regarding age/gender, and the selected study population [5].
Generally, > 25% of the asymptomatic population undergoes colonoscopy, while screening colonoscopy with polypectomy has been shown to reduce CRC incidence and mortality [13]. A systematic review and meta-analysis study by Heitman et al., 2009 showed that adenoma was estimated at 30.2% in average-risk adults [9]. Previously, the data have shown a higher incidence of colon polyps and CRC in western countries [7]; however, there has been a significant rise in colon polyps and CRC in eastern countries, which might be attributed to lifestyle and diet changes [5].
According to the current study, the prevalence of colorectal polyps was 14.3%, with male predominance and a proportional increase in prevalence with increasing age, with a more than two-fold increase in prevalence in patients above 40 years, 69.2% of polyps were found in the left colon, while 21.4% were in the right colon, with the rectum being the most abundant site for polyps. Another study in Iraq showed similar prevalence rates of colorectal polys, 16% in Erbil [14] and 16.44% in Karbala [15]. However, with male predominance in the former study, while in the latter, females had a higher prevalence of 17.89% vs 15.43%. Moreover, Feyzullah et al., 2016 in a five-year evaluation of the Southeast Anatolian region, Turkey, reported 13.3% (470/3514) of colon polyps, with 61.7% being male patients [12]. A similar study in Iran by Sohrabi et al., 2014 shows a 16.5% prevalence of polypoid lesions in 199/1208 patients that underwent colonoscopy [10].
Regarding Asian countries, a cross-sectional study by Pan et al., 2020 in China mentioned that 3066 cases underwent colonoscopy, from which 554 (18.1%) patients had polyps [5]. Another prospective study in China by Liu et al., 2005, reported a prevalence of 971/5973 (16.3%) of colorectal polyps with a mean age of 56.6 ± 10.7 which is close to the mean age of our studied patients with polyps (52.0 ± 17.59 years) [16]. Both studies noted that older subjects had higher rates of colorectal polyps. While in India, a lower rate of polyps was recorded in a large retrospective cohort study (10.18%) [17]. In a single hospital-based retrospective study, 11.0% of polyps were observed in 14.7% of patients aged > 40 years [11].
Polyp number was another aspect of this study, in which most patients (68.5%) had a single polyp, while 31.5% had more than one polyp anywhere in the colon. In the studies of Pan et al., 2020 [5], Hussein Al-Jameel et al., 2020 [15], and Lebwohl et al., 2012 [18], multiple polyps were seen in 32.7%, 25.9%, and 23% of patients, respectively.
Regarding the polyp location in the current study, most polyps were identified in the rectum, followed by the sigmoid colon. Whereas a study by Liu et al., 2005, showed that most polyps are located in the distal colon (58.6%), followed by the proximal colon (29.2%), and combined (12.2%) [16].
Consequently, the histopathological examination of polyps revealed the highest rate of tubular adenoma (69.6%), followed by hyperplastic polyps (24.5%), tubulovillous and villous adenomas were found in 3.92% and 1.96% of polyps, respectively. In a study in Duhok, Iraq, the ratio of hyperplastic polyps in the large intestine was 30.7% of all non-neoplastic polyps. In comparison, tubular adenomas constituted 93.02% of neoplastic polyps in the large intestine, and tubulovillous and villous adenomas were 2.99% and 0.93%, respectively [19]. Furthermore, another study reported that the ratio of hyperplastic and adenomatous polyps was 31.7% and 53.6%, respectively. They also subdivided adenomatous polyps into tubular 215/252 (85.3%), tubulovillous 32/252 (12.69%), and villous 5/252 (1.98%) [12]. In Tehran, Iran, 86.9% of polyps were found to be adenomatous, among which 69.8% were tubular, 7.53% were tubulovillous, 2% were villous adenoma, and 13% were non-neoplastic adenoma [10]. In another study on tiny polyps in the sigmoid and rectum in a Colombian population, 51.0% were found to be tubular adenomas, 0.8% tubulovillous, and 43.3% were hyperplastic adenomas [20]. Moreover, Jayadevan et al. 2016; reported that 41.8% of patients had adenomatous polyps, and 49.5% had hyperplastic polyps [11].
These results showed that the prevalence of colorectal polyps in our locality is comparable with the countries in the region and other Asian countries but still lower than in Western countries, which may be related to the lifestyle of the populations, including diet, ageing population, obesity, or difference in screening programs among these countries and even design of the studies. Thus, further studies are needed to confirm the influence of these factors on the prevalence of colorectal polyps in this region.