Keywords
Colonoscopy - Adenoma - Adenoma with Advanced Pathology - Colorectal Cancer - Screening
- India
Introduction
Colorectal carcinoma (CRC) is a common public health problem worldwide. The overall
prevalence of CRC in Asian countries and India is reported to be low compared with
Western countries.[
1
] With industrialization and changing socioeconomics in Asia, the burden of CRC in
increasing.[
2
]
[
3
] The age-standardized incidence of CRC in India increased from 4.3 in 2008 to 7.2
per 100,000 male population in 2012. It is expected to rise by 60% in males and 37%
in females by 2026.[
4
]
[
5
]
Colonic adenomas are recognized as precursor of majority of CRCs through adenoma carcinoma
sequence.[
6
] The prevalence of colonic adenoma in the Western population of age more than 50
years is 20% to 53%.[
7
] This prevalence is concordant with CRC prevalence in the population. The US National
Polyp Study demonstrated that colonoscopy and polypectomy could prevent 76% to 90%
of colorectal adenomas.[
8
]
There is limited data on prevalence of colorectal adenoma from Indian subcontinent.
The prevalence of colonic adenoma in India is between 5.4% and 6.7%.[
9
]
[
10
] However, both the studies were single-center and of small sample size. In the current
study, we aimed to evaluate the prevalence of colorectal adenoma and histopathological
characteristics of colonic polyps in a retrospective cohort.
Methods
The institutional review board has approved the study. All consecutive adult patients
(age > 18 years) who underwent colonoscopy between January 2018 and December 2020
at a tertiary care center were screened for analysis. Patients with at least one colonic
polyp were included in the study. The baseline demographic characteristics included
age and sex along with colonoscopic and histological characteristics of polyp, which
were collected from endoscopic and histopathological database.
Colonoscopies were performed after standard preparation of 2 L of polyethylene glycol
by senior gastroenterologist and trainee gastroenterologist under supervision of former.
Quality of colonoscopy preparation was assessed by the Boston bowel preparation scale.
[
11
] Patients with poor or inadequate preparation were advised for repeat colonoscopy
on subsequent day after repeat preparation. There was no fixed protocol about colon
withdrawal time during study period; it was as per discretion and satisfaction of
endoscopist.
Patients with anal canal or ileal polyps and colonic polyps, where histological characteristics
were incomplete or unavailable, were excluded from analysis. Patients who underwent
screening colonoscopy or incomplete colonoscopy without obstructive lesion were also
excluded. We excluded patients who underwent screening colonoscopy , those who previously
underwent colonoscopic polypectomy or colorectal surgery for CRC, and those with family
history of CRC, as these patients are considered as high risk for colorectal adenomas.
After histopathological characteristics, colonic polyps were classified into adenocarcinoma,
adenomatous polyps or nonadenomatous polyps. The standard definitions were used to
characterize histologically different types of polyps.[
12
]
[
13
] Adenomatous polyps were considered as adenoma with advanced pathology (AAP), if
size was more than 10 mm, villous morphology or high-grade dysplasia. If these features
were absent, these were considered as nonadvanced adenomas (nAAP). Patients with multiple
polyps were grouped in adenocarcinoma, AAP, or nAAP, if at least one polyp had features
of one the mentioned subgroup.
Results
A total of 36426 colonoscopy were performed between January 2018 to December 2019,
of which 1533 were excluded for following reasons: incomplete colonoscopic examination
without obstructive lesions, screening colonoscopy and incomplete histopathological
reports. The common indications for colonoscopy were unexplained abdominal pain (2646;
74.5%), anemia (206; 5.8%) per rectal bleeding (873; 24.6%), weight loss (163; 4.6%),
and evaluation for liver or lung metastasis (36; 1%).
Overall colon polyp prevalence was 10.18% (3551/34893; 18.08% more than one polyp).
The mean age (SD) was 51.51 (14.84) with 75.4% males, of which 128 (3.6%) were adenocarcinoma.
A total of 1514 (42.64%) were adenomas; 344 (9.7% of total polyps) were AAP, and 1170
(32.9% of total polyps) were nAAP. The remaining 1909 (53.8%) were nonadenomas. Colonic
adenoma prevalence after excluding adenocarcinoma was 4.35% (1514/34893). Adenocarcinoma
(68.8% vs. 31.2%), AAP (70.6% vs. 29.4%), nAAP (75.4% vs. 24.6%), and nonadenomas
(76.7% vs. 23.3%) were significantly higher in males compared with females (p 0.05). [Table 1] depicts summary of the study population. The mean age (SD) were significantly lower
in nonadenomas than adenocarcinomas, AAP, and nAAP (p 0.0001; 48.25 [15.75] vs. 55.97 [12.47], 54.29 [17.59], 53.66 [15.75]). The location
of adenocarcinoma was rectum in 37 (28.91%), left colon which included sigmoid and
descending colon 48 (37.5%), and right colon which included cecum, ascending and transverse
colon 43 (33.59%) patients. There was no significant difference in age of patients
with adenocarcinoma location in rectum or left colon (54.60 ± 12.75) and right colon
(58.67 ± 11.57; p 0.081).
Table 1
Summary of the study population (n = 3551)
|
Parameter
|
Adenocarcinoma
(n = 128)
|
AAP
(n = 344)
|
nAAP
(n = 1,170)
|
Nonadenoma
(n = 1,909)
|
|
Abbreviations: AAP, adenoma with advanced pathology; IQR, interquartile range; nAAP,
adenoma without advanced pathology.
|
|
Age, mean (IQR) years
|
55.97 (47–65)
|
54.29 (45.25–66)
|
53.66 (45–63)
|
48.92 (39–61)
|
|
Sex
|
|
|
|
|
|
Male, n (%)
|
88 (68.8)
|
243 (70.6)
|
882 (75.4)
|
1465 (76.7)
|
|
Female, n (%)
|
40 (31.2)
|
101 (29.4)
|
288 (24.6)
|
444 (23.3)
|
|
Location
|
|
|
|
|
|
Rectum, n (%)
|
37 (28.9)
|
122 (35.5)
|
275 (23.5)
|
716 (37.5)
|
|
Left colon, n (%)
|
48 (37.5)
|
166 (48.3)
|
484 (41.4)
|
708 (37.1)
|
|
Right colon, n (%)
|
43 (33.6)
|
56 (16.3)
|
411 (35.1)
|
485 (25.4)
|
There were total 1514 (42.64%) adenomas, of them 344 (9.7%) were AAP and 1170 (32.9%)
were nAAP. Tubular adenoma was the most common histological type with 1241 (81.97%),
followed by tubulovillous 177 (11.69%), and villous 96 (6.3%). Of 1241 tubular adenomas,
71(5.7%) were either showing high-grade dysplasia or size more than 10 mm. In tubulovillous
and villous adenoma, high-grade dysplasia or size more than 10 was seen in 52.38%
(143/273) patients. The mean (SD) age of patients with adenoma was 53.80 (14.88) years.
The interquartile range was 45 to 64 years. [Table 2] depicts age-wise distribution on colonic polyps. The proportion of nonadenoma polyps
were higher than adenomatous polyps in patients of age less than 50 years; between
51 to 60 years, proportion of adenoma and nonadenoma appears comparable, and after
60 years, proportion of adenomatous polyps is more than nonadenomas. In nonadenomatous
polyps (1909), hyperplastic (n = 925; 48.45%) and inflammatory (n = 820; 42.96%) polyps were the most common. The remaining 164 (8.59%) were hamartomatous,
benign epithelial, lipomatous, lymphoid, and carcinoids. Nonadenomatous polyps were
more in rectum or left colon compared with right colon (74.59% vs. 24.41%, p 0.0001).
Table 2
Age-wise colonic polyp distribution
|
Age group
|
Adenocarcinoma (n = 128)
|
AAP
(n = 344)
|
nAAP
(n = 1,170)
|
Non adenoma
(n = 1,909)
|
Total
(n = 3,551)
|
|
Abbreviations: AAP, adenoma with advanced pathology; nAAP, adenoma without advanced
pathology.
|
|
< 40 years
|
12 (9.4%)
|
64 (18.6%)
|
204 (17.5%)
|
538 (28.2%)
|
818 (23.1%)
|
|
41 to 50 years
|
30 (23.4%)
|
58 (16.9%)
|
232 (19.8%)
|
409 (21.4%)
|
729 (20.5%)
|
|
51 to 60 Years
|
34 (26.6%)
|
77 (22.4%)
|
335 (28.6%)
|
474 (24.8%)
|
920
(25.9%)
|
|
> 60 years
|
52 (40.6%)
|
145 (42.1%)
|
399 (34.1%)
|
488 (25.6%)
|
1084 (30.5%)
|
Discussion
Colonic polyps is one of the common findings during colonoscopy. There is scarcity
of data from India about colonic polyps detected during colonoscopy. In the current
study, colon polyp prevalence is 10.18%, of which 42.64% were adenomas. Overall adenoma
prevalence was 4.35%, with mean age (interquartile range [IQR]) of 53.80 (45–64) years.
No-adenoma polyps were the most common type of polyps in the present study. Mean age
was significantly lower in nonadenoma polyps compared with adenocarcinomas and adenomas.
All types of polyps were more common in males and in rectum or left colon.
Majority of CRC arose from adenomatous polyps.[
2
] Adenoma detection by colonoscopy and removal by polypectomy can prevent CRC.[
1
]
[
2
]
[
6
] The prevalence of adenoma varies with patients’ age, sex and family history but
is concordant with background rate of CRC in the population.[
14
] Age is the most important independent determinant of adenoma prevalence.[
15
]
[
16
] The adenoma prevalence in current study was 4.35% with mean age (IQR) of 53.80 (45–64)
years. Previous studies from India reported 6.73% adenomas (12.7% overall polyps).[
10
] In a large series from western India, adenoma prevalence was 5.43% (10.3% overall
polyps) with mean age of 59.5 (14.8) years.[
9
] The IQR for adenoma in the current series is 45 to 64 years.
In a series of 515 colorectal polyps from western India, 270 (52.4%) were adenoma,
15 (2.9%) were adenocarcinoma, and hyperplastic and inflammatory polyps were 15% each.[
9
] In our series of 3551 patients, 1514 (42.64%) were adenomas, 1909 (53.8%) were nonadenomas,
and 128 (3.6%) adenocarcinoma. Similar to previous studies, we also found tubular
adenoma and male preponderance among adenomatous polyps.[
9
]
[
10
] As compared with Western data, the overall prevalence to colonic adenoma appears
lower in Indian population; however, within colonic adenoma, proportions of tubular,
tubulovillous and villous adenomas appear comparable.[
7
]
[
17
]
The prevalence, incidence, and case fatality of CRC varies in Asian countries.[
1
] Japan, Korea, China, and Thailand are more affected by CRC compared with India,
Indonesia and Vietnam.[
18
] The five-year prevalence of CRC in Japan, Malaysia, Singapore, China and Korea is
higher than in other Asian countries (> 46.5/100,000)[
18
] as compared with 8.3/100,000 in India.[
1
]
[
18
] Recent estimates suggest increasing trend of CRC in India by 2026. Age-standardized
incidence of CRC in India in expected to increase by 60% in males and 37% in females.[
4
]
[
5
] Considering India’s vast population, and with increasing Westernization of lifestyle,
CRC may emerge as public health problem. Colonoscopy and polypectomy can be simple
and effective tool to prevent CRC, a well-established practice in the West.[6]
[7]
[8]
Apart from being a single-center and retrospective study, the current study has certain
other limitations. We have not evaluated other risk factors such as family history,
diet and lifestyle, including smoking, in the current study. There was no fixed protocol
about colon withdrawal time during study period; it was as per discretion and satisfaction
of endoscopist. We also do not have data on cecal intubation rate, as incomplete colonoscopies
were not included in the analysis.
This large sample study highlights the need to develop a screening colonoscopy program.
Male gender and increased age were associated with increased risk of colonic adenoma
and adenocarcinoma, which is more common in left colon and rectum. As prevalence of
CRC is increasing, a prospective, multicenter study is required to define average
and high risk population in the Indian population.
