Demographic And Histopathological Characteristics Of Colorectal Polyps: A Descriptive Study Based On Samples Obtained From Symptomatic Patients

During 2011-2014, 1100 the patients aged ≥ 20 years were referred by a family doctor or gastroenterologist to undergo a colonoscopy examination in relation to their symptoms (hematochezia, melena, positive fecal occult blood, abdominal pain, constipation or chronic diarrhea). A total of 67 patients (69.8% men) were excluded due to the presence of CRC and another 766 patients (48.9% men) were excluded due to the negative findings (lack of popyls) during the examination. The study population comprised 267 individuals (64.8% men) with at least one diagnosed and resected polyp. The patients with colorectal cancer were the oldest (mean age 62.7 years) and those with negative findings were the youngest (mean age 49.9 years).

Colonoscopy examinations were performed by two doctors. Any time a polyp was identified, a polypectomy procedure followed. In case of suspected malignancy, a cold forceps biopsy was obtained. The procedure was performed with Narrow band Imaging (NBI, EVIS EXERA II CV-180 Olympus™), high definition endoscopes and without the use of chromo-endoscopy during the identification procedure. Opened biopsy forceps of 7 mm and opened polypectomy snare with known diameter were used for measuring the polyps before piecemeal resection. Cold forceps and cold snare have been the polypectomy methods of choice for smaller polyps, and hot snare has been the method of choice for larger polyps.

All specimens were histologically examined by a pathologist and, when in doubt (26 cases), a second, experienced pathologist was called to help reaching a decision. First, we measured the height and diameter of each specimen. After that, we put them in formalin solution. Once fixed, the specimen was sectioned in such a way that the relationship of the stalk to the head of the polyp was clear. To avoid missing a small focus of carcinoma, the entire specimen was submitted for histologic evaluation. The sections were stained with hematoxylin eosin (HE). All slides were examined under a light microscope (4X, 10X and 40X dry objectives).

The 2010 World Health Organization (WHO) criteria were applied to assess the grade of dysplasia and architecture of the polyps (10). Adenomatous polyps were divided into low-grade or high-grade dysplasia. Depending on the presence and volume of villous tissue, adenomatous polyps were further classified as tubular, tubulovillous or villous.

The presence of hypercellular stroma, large mucin-filled cysts, the lack of smooth muscle core and flattened epithelium were used as criteria to diagnose a juvenile polyp. Finally, the presence of various degrees of inflammatory infiltrate, ulceration, edema and granulation tissue were the criteria on the basis of which the diagnosis of an inflammatory polyp was made.

Continuous variables are presented as mean and standard deviation (SD), while categorical variables are presented as numbers and proportions. Independent sample t-tests were used for comparisons of continuous, normally distributed variables. Categorical variables were compared using the chi square test. Two-sided tests with a 0.05 significance level were used. All statistical analyses were performed using STATA 13 (Stata Corp LP, 4905 Lakeway Drive, College Station, Texas, USA).

There were no statistically significant gender difference with regard to age (p=0.22) and polyp size (p=0.84). Adenomatous polyps were more frequent among men compared to women (p=0.02) (Table 1). When analyzed separately, we did not observe gender differences in the distribution of non-adenomatous polyps (p=0.92), while adenomas were distributed differently between men and women (p<0.01). The tubular type accounted for 79.1% of all adenomas among men and only for 46.6% of them among women (Table 2).

Overall, non-adenomatous polyps were smaller than adenomas (p<0.01). Small polyps (< 1 cm) comprised the absolute majority (82.8%) of non-adenomatous polyps, while the distribution of adenomas with regard to size was more proportional. Middle-sized polyps (1-2 cm) accounted for 44.5% of cases, followed by small (32.3%) and large (> 2 cm) ones (23.2%) (Table 3).

We did not observe any gender differences with regard to size when analyses were conducted separately among non-adenomatous polyps (p=0.52) and adenomas (p=0.71) (Figure 1).

Figure 1

A linear relationship was observed between patient age and type of polyp. Adenomas were more frequent than non-adenomatous polyps among all age groups, but this difference tended to increase with age (p<0.01) (Figure 2).

Figure 2

Age was also associated with subtype distribution among adenomas; tubular subtype accounted for 89.2% of all adenomas among patients < 45 years, but this proportion dropped with increasing age to 74.8% among patients 45-65 years and further to 59.7% among those > 65 years. On the contrary, the proportion of villous subtype - the most important CRC precursor - increased from 1.5% among patients < 45 years to 13.9% among those older than 65 years (p=0.01) (Figure 3).

Figure 3

Lastly, we explored the association between grade of dysplasia and patient age, and observed that older patients showed more often adenomas with high-grade dysplasia compared to their younger counterparts (p=0.008). However, high-grade dysplasia was not uncommon among young and middle-aged patients, and accounted, respectively, for 29.2% and 43.2% of all adenomas in these groups (Table 4).

To date, there is a general consensus on the beneficial role of screening average-risk individuals in their 50s every 10 years. Different suggested approaches (opportunistic or programmatic screening) help preventing CRC by removing polyps with high malignant potential (3) or detect CRC at an early stage, improving its prognosis. To illustrate, the 5-year survival is 90% if CRC is diagnosed early (while still localized) and only 10% in advanced stages when distant metastases develop (18).

We showed that the proportion of patients with high-grade dysplasia and size > 1 cm accounted for ~ 56% of patients older than 65 years. However, such adenomas with high malignant potential were not exclusively observed among older adults. They accounted for nearly 1/3 of adenomas observed among younger (< 45 years) and 40.3% of those observed among middle-aged (45-65 years) patients. Further, adenomas with a villous component (either tubulovillous or villous) accounted for ~ 10% of adenomas among patients < 45 years and 1/4 of those among patients 45-65 years. These results show clearly a potentially beneficial role of conducting screening programs among individuals in their fourth to fifth decade of life in order to identify polyps with high malignant potential and reduce the burden of CRC in Albanian population.

Our study is the first national study and one of the few recent analyses worldwide (16, 17) exploring histopathological characteristics of colorectal polyps and their distribution. However, it carries certain limitations, among which it is worth mentioning that the study population comprises consecutive symptomatic patients and not a representative national sample. Moreover, additional information on the disease stage would provide additional valid evidence. Further, we do not know the type and distribution of such polyps among the severe cases that died before undergoing colonoscopy examination.