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Table of Contents
Year : 2021  |  Volume : 13  |  Issue : 1  |  Page : 18-22

Screening for colorectal cancer in Nigeria: A survey of gastroenterology practitioners

1 Department of Internal Medicine, University of Calabar, Calabar, Cross River State, Nigeria
2 Department of Internal Medicine, Lagos State University, Lagos, Nigeria

Date of Submission02-Aug-2020
Date of Decision27-Apr-2021
Date of Acceptance06-May-2021
Date of Web Publication30-Jun-2021

Correspondence Address:
Dr. Uchenna Okonkwo
Department of Internal Medicine, University of Calabar, P.M.B. 1115, Calabar, Cross River State
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njgh.njgh_22_20

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Background: Colorectal cancer (CRC) is common in Africa including Nigeria contrary to popular opinion. Screening for CRC is cost-effective and reduces morbidity and mortality.

Aim: The aim of the study was to assess the practice of CRC screening among gastroenterology practitioners in Nigeria.

Methods: This was a questionnaire-based cross-sectional descriptive study conducted among gastroenterology practitioners attending their annual conference in 2016. Data were analyzed using SPSS version 20.

Results: A total of 65 respondents completed the questionnaire. The mean age was 37.68 years. Majority (95%) of the respondents practised in tertiary hospitals. Screening for CRC was practised by 54% of the respondents, with colonoscopy and guaiac fecal occult blood test being the preferred screening modalities. Indications for screening were mostly symptom based with varied protocols and outcomes.

Conclusion: The practice of CRC screening among gastroenterology practitioners in Nigeria is variable. There is a need to formulate national guidelines and colonoscopy quality control tools to improve awareness and standardize practice.

Keywords: Colorectal cancer, Nigeria, screening

How to cite this article:
Okonkwo U, Onyekwere C. Screening for colorectal cancer in Nigeria: A survey of gastroenterology practitioners. Niger J Gastroenterol Hepatol 2021;13:18-22

How to cite this URL:
Okonkwo U, Onyekwere C. Screening for colorectal cancer in Nigeria: A survey of gastroenterology practitioners. Niger J Gastroenterol Hepatol [serial online] 2021 [cited 2023 Mar 21];13:18-22. Available from: https://www.njghonweb.org/text.asp?2021/13/1/18/320304

  Introduction Top

Colorectal cancer (CRC) is the third most common cancer with a global annual incidence of approximately 1.8 million cases and a mortality of >500,000/year.[1] CRC was previously thought to be uncommon in Africans because of the African diet which is rich in fiber and bran. However, contemporary studies have shown this to be largely untrue as CRC is indeed common in Africa including Nigeria and unlike in western countries where it frequently occurs in the sixth and seventh decades of life, it occurs in persons under the age of 50 years.[2],[3] Reports from Western Nigeria indicate that CRC is now the most common gastrointestinal malignancy.[3] This has been attributed to increased westernization of the African diet, increased cancer awareness, and availability of screening tools.

CRC is distinctive as it usually starts as innocuous growths in the lining of the bowel known as polyps. Eventually, these polyps may become malignant after several years especially in persons with the genetic predisposition or under the influence of some environmental factors which include increase intake of red meat, high-fat and low-fiber diet and smoking, and high alcohol consumption among others.[1] There are two types of CRC – sporadic and familiar. Heritable mutations account for only a small proportion of CRCs and as such genetic testing may only be beneficial to a minor population of potential CRC cases.[4]

Sporadic mutation is responsible for majority of CRCs and it is preventable and curable if detected at an early stage; thus, screening is essential. Screening entails the use of appropriate investigative tools to detect early-stage CRCs and dysplastic lesions in asymptomatic people with no prior history of cancer or precancerous lesions and several tests can be used to achieve this though their efficacy, feasibility, and affordability are highly variable. Colonoscopy a process which involves direct visualization of the entire large bowel using fiber-optic flexible telescopes remains the gold standard for detection and removal of premalignant and dysplastic polyps, thereby preventing the development of advanced cases of cancer.[5] Its sensitivity and specificity approach 100%; however, it is operator dependent, cost-intensive, requires considerable patient and health-care provider effort, and may be complicated by perforation, bleeding, and aspiration pneumonia.[6]

CRC is known to shed microscopic blood in stool prior to the appearance of clinical symptoms. Stool-based tests such as guaiac fecal occult blood test (gFOBT) detect peroxidase activity of heme with a sensitivity of 50%–60% for a single-time use.[7] However, the test also reacts with peroxidases from certain fruits, vegetables, and red meat limiting its specificity. Fecal immunochemical test (FIT) which detects hemoglobin in stool and fecal deoxyribonucleic acid (fDNA) test are newer stool-based tests. While FIT is less cost-intensive with a sensitivity and specificity of 79% and 96% for a one-time test, fDNA is more cost-intensive, employs variable sets of molecular markers, and has a sensitivity of 52% and specificity of 95%. When combined, the FIT-fecal DNA test has a one-time sensitivity for CRC of 92% with no significant improvement in specificity (86.6%) and cost.[8],[9],[10] Radiological tests such as barium enema and computed tomography (CT) colonography are reasonable alternatives to colonoscopy but are less sensitive (50% for barium enema, 82%–92% for CT colonography), cost-intensive, and require significant patient effort (bowel preparation).[7] In addition, they lack therapeutic value along with the stool-based tests.

According to the World Gastroenterology Organization (WGO), it is recommended that adults above the age of 50 years undergo colonoscopy every 5- to 10 years because it has been shown that the peak age incidence of CRC in adults (men and women) is in the fourth decade of life except for persons of African descent and those with a family history of CRC in whom screening should commence at a younger age.[11],[12] Screening of those at average-to-high risk has been shown to be cost-effective in reducing mortality from CRC.[13] The evidence base for this exceeds that for other common malignancies that are widely screened for, such as, breast, cervical, and prostate cancers.[14],[15] It is projected that low- and middle-income countries will experience a 70% increase in CRC by the year 2030.[1] The converse is true in most high-income countries because of effective screening strategies. In Nigeria as in most other countries, diagnosis and management of CRC is the responsibility of gastroenterology practitioners (medical or surgical). Thus, they are best suited to provide insights into screening practices regarding CRC in our environment.

Aim and objective

The aim of the study was to assess the practice of CRC screening among gastroenterology practitioners in Nigeria.

  Methods Top

This was a questionnaire-based cross-sectional descriptive study conducted among gastroenterology practitioners attending their annual conference in 2016. Only those who practise in Nigeria were included in the study. Screening recommendations used in the study questionnaire were based on WGO guidelines.[11] Data were analyzed using the Statistical Package for social sciences (SPSS) version 20 SPSS, Inc. Chicago, Illinois, USA. Categorical variables were analyzed using frequencies and percentages and continuous variables with mean and standard deviation. Association between categorical variables was analyzed using Chi-square. Statistical significance was set at P < 0.05.

  Results Top

A total of 65 respondents completed the questionnaire. The mean age was 37.68 years. The age range with the highest frequency was 31–40 years (59.4%), followed by 41–50 years (26.6%), 21–30 years (10.9%), and S805;50 years (3.1%). Majority (95%) of the respondents practised in tertiary hospitals and most (61%) were young practitioners with ≤10 years of gastroenterology practice, while 27% were senior registrars in training. The study population comprised 52% of physicians, 34% of surgeons, 2% of pathologists, and 12% with unspecified specialty. Screening for CRC was considered important by 98.5% of the respondents, but only 55% considered it cost-effective. Fifty-four percent were screened for CRC while 46% were not screened for CRC. The reasons impeding screening are shown in [Table 1]. The association between duration of practice and screening for CRC was not statistically significant (P = 0.68).
Table 1: Factors impeding screening for colorectal cancer

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Of those who were screened for CRC, indications for screening were mostly symptom based [Table 2]. The preferred screening modality employed was colonoscopy (84.6%) followed by FOBT (53.8%). Other screening modalities are shown in [Figure 1]. For those who were screened using FOBT, recommended dietary restrictions before performing the test were always prescribed by 48.6%, sometimes prescribed by 22.9%, and rarely prescribed by 28.6%. More than half of the respondents (56.3%) would request only a single stool sample for FOBT, while 43.7% requested two or three consecutive stool samples. Spontaneous stool collection was preferred to digital rectal examination (94% versus 6%). Following a positive FOBT result, 100% would go ahead and request a colonoscopy while following a negative FOBT result, the interval before a repeat test was variable [Table 3].
Table 2: Indications for screening for colorectal cancer

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Figure 1: Preferred screening modality for colorectal cancer. FOBT– Fecal occult blood test, CT – Computerized tomography, DCBE – Double-contrast enema, FIT – Fecal immunohistochemistry test, FDT – Fecal deoxyribonucleic acid test

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Table 3: Interval before requesting a repeat fecal occult blood test following a negative result

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For those who were screened for CRC using colonoscopy, bowel preparation was usually achieved with a combination of dietary restriction and any of these: stimulant laxative (51%), polyethylene glycol (56.3%), and mannitol (20%). Cecal intubation was achieved in <1 h by 53.3%, 1–2 h by 33.3%, and in >2 h by 13.3% of the respondents. Only 13% achieved a cecal intubation rate of >90%. Although majority (83.3%) of those who achieved cecal intubation rate of >90% achieved it (cecal intubation) in <1 h, the association between cecal intubation rate and time was not statistically significant (P = 0.087). Polyp detection rate of <5% was reported by approximately 50% of the respondents [Figure 2]. The association between polyp detection rate and cecal intubation rate was not statistically significant (P = 0.55). Most of the respondents (90.2%) would always take biopsies from a suspicious lesion seen on colonoscopy. However, the number of biopsy specimens taken was usually not optimal as only 39.6% would take six specimens according to Sydney's recommendation, 37.5% would take four specimens, while 18.8% and 2% would take only two and one biopsy specimen, respectively. In the event of a negative finding, a repeat colonoscopy was requested for annually by 13.7%, after 5 years by 52.9%, after 10 years by 15.7%, and never again by 17.6%.
Figure 2: Polyp detection rate. NB: Polyp detection rate of <5% was reported by 48.6% of respondents, polyp detection rate of 5%–10% by 20% of the respondents, polyp detection rate of 11%–15% by 8.6% of the respondents, polyp detection rate of 16%–20% by 14.3% of the respondents, polyp detection rate of 20% by 8.6% of the respondents

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  Discussion Top

CRC screening is complex as there are multiple options and some require considerable patient and health-care provider effort. Most of the respondents practise in teaching hospitals which are mostly situated in urban areas and this is reflective of the skewed distribution of specialist health care in the country.[16] A good number of respondents do not consider CRC screening cost-effective. This may be due to underdiagnosis and late presentation occasioned by poor health literacy as most persons would rather resort to faith-based healing or traditional remedies when faced with serious ailments such as cancer.[17]

For those who were screened for CRC, indication for screening was largely symptom based as previously reported.[16],[18] The WGO had cascaded the screening protocol to highlight not only the average-high risk population but also best practices in terms of screening options vis-à-vis availability and national gross domestic product.[11] This study showed that colonoscopy is a widely acceptable screening tool; however, quality is questionable as there were wide variabilities in the reported outcomes. The low yield of colonoscopy in this study may be attributed to some of the respondents being trainees. Nonetheless, it is evident from this study that colonoscopy is unlikely to be available at the secondary and primary levels of health-care delivery as most of the respondents practise in tertiary health-care institutions. This has been reported by previous studies.[18] Thus, a large percentage of the population will be excluded from screening using only colonoscopy as a first-tier screening test. Alatise et al.[19] put up a very comprehensive document on “Management of CRC in Nigeria” in 2016. The authors recommended colonoscopy and FIT as first-tier screening tests for CRC. Our study showed that FIT is largely unpopular among gastroenterology practitioners because it is not routinely available and affordable. A recent study suggested that endemic intestinal parasites and high ambient temperatures may alter the performance of FIT in the tropics.[20] FOBT, on the other hand, is popular, available, affordable, and easy to perform with minimal patient and health-care provider effort and would be a preferred first-tier screening test compared to FIT. The sensitivity and specificity of FOBT are largely improved if multiple stool samples are collected and dietary restrictions adhered to prior to stool collection.[21] This study identified gaps in the method of stool collection for FOBT. It is recommended that heme containing food substances and medications be restricted prior to collecting samples for FOBT, and preferably, three consecutive stool samples should be collected for best results.[21]

Although colonoscopy was the preferred screening tool, availability of colonoscopy services is limited by infrastructure and manpower; a situation observed in other low-/middle-income countries[22] Methods of bowel preparation, cecal intubation rate, and polyp detection rate varied significantly among the respondents and are similar to previous reports.[18] It has been reported that each 1% increase in adenoma (polyp) detection rate (ADR) is associated with a 5% decrease in the risk of fatal interval CRC.[23] Polyp detection rate reported from different colonoscopy centers in Nigeria varies from 6.8% to 23.2% reflecting wide variability in quality, as was observed in this study.[18],[24],[25] There is a need to develop and introduce colonoscopy quality control instruments/tools for use by all colonoscopy centers in the country as this has been shown to impact positively on ADR.[26] Nonadherence to recommended biopsy protocol would likely impact negatively on the quality of histopathological examination and identification of high-risk dysplasias.[27]

  Conclusion Top

The practice of CRC screening among gastroenterology practitioners in Nigeria is not optimal. The indication for screening is mostly symptom based with a variable performance of both colonoscopy and gFOBT. Optimal results in CRC screening will require the formulation of national guidelines and colonoscopy quality control tools to improve awareness, standardize the technical performance and reporting of tests, and ensure appropriate patient follow-up after testing.


Cecal withdrawal time, a major determinant of polyp detection rate, was not assessed.


We acknowledge Drs E. Chukwudike and M. Ada for assisting with data collection.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3]


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