











































 
 
 
 
 

 
www.companyofscientists.com/index.php/chd                   e1                                              Cancer Health Disparities 

RESEARCH 

Quality of evidence on prostate cancer in 
Nigeria 
Omolara Aminat Fatiregun*1,2, Frank Chinegwundoh1,3, Proffessor Nicholas D James1,4, Odunayo 
Ikuerowo1,5, Olufunmilade Omisanjo1,5, Abimbola Abolarinwa1,5, Anthonia Chima Sowunmi1,6, Funlayo 
Buraimoh1,7, Folakemi Odedina1, 8 

1 Prostate Cancer Transatlantic Consortium,2 Oncology Unit, Department of Radiology, Lagos state 
University College of Medicine, Ikeja, Lagos, Nigeria 3 Department of Urology, Barts Health, National 
Health Service Trust, London 4 University Hospitals Birmingham NHS Foundation Trust, The Medical 
School, University of Birmingham, Birmingham, UK 5 Department of Surgery, Lagos State University 
College of Medicine/ Lagos state University Teaching Hospital, Ikeja, Lagos, Nigeria 6 Department of 
Radiotherapy & Oncology, Lagos University Teaching Hospital/ University of Lagos, Lagos, Nigeria. 
7Department of Biochemistry, Lagos State University College of Medicine. 8 Department of 
Pharmacotherapy and Translational Research and Department of Radiation Oncology, University of 
Florida, Lake Nona Campus, FL, 32832, USA 

*Corresponding author email: omolarafatiregun@gmail.com. 

Prostate cancer is the 2nd commonest malignancy in men worldwide. It is, however, the commonest in 
Nigeria. While several disparities have been documented between Caucasian men and men of African 
descent, there is limited research on prostate cancer in Nigeria. Evidence based medicine is a key tool in 
making clinical decisions and developing screening and treatment guidelines. This review was 
undertaken to assess the levels of evidence on prostate cancer research in Nigeria. A systematic review 
of all research published on prostate cancer from January 1975 to May 2018 in Nigeria was conducted. 
We reviewed all articles found on various databases by searching for “Prostate cancer in Nigeria”. We 
classified them based on their study designs into different levels of evidence as well as year of 
publication. Meta-analyses were not considered in the review. A total of 171 articles were eligible for this 
review. Most publications were at the 4th (66%) and 5th levels of evidence (17%) respectively. No clinical 
trials on prostate cancer in Nigeria was seen or registered on clinicaltrials.gov, hence no studies at level 
1 (a, b or c) of evidence published in Nigeria. The commonest type of study design was cross-sectional 
studies accounting for 56% of all publications. Prostate cancer research is currently at low levels of 
evidence in Nigeria. It is pertinent to explore and increase funding channels for cancer related research. 

KEYWORDS: Prostate,cancer, Nigeria. 

Citation: Fatiregun et al (2019) Quality of evidence on prostate cancer in Nigeria. Cancer Health Disparities. 
4: e1-e9. doi:10.9777/chd.2019.1005 
 



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd                   e2                                              Cancer Health Disparities 

RESEARCH 

INTRODUCTION 

In 2012, an estimated 14.1 million new cases of cancer 
were diagnosed worldwide. Prostate cancer was the 
second most prevalent malignancy in men after lung 
cancer worldwide. It is the fifth most common cause 
of cancer deaths (Ferlay et al., 2015). In Nigeria, it is 
the commonest malignancy in men and its incidence 
continues to rise (Elima et al., 2012; Adeloye et al., 
2016). Globally, several disparities have been 
documented between Caucasian men and men of 
African descent. These include an increased risk of 
developing prostate cancer in Black men, younger 
age of incidence in Black men, and genetic 
differences. These factors might have an impact on 
survival outcomes (Odedina et al., 2009; Brawley, 
2012). Prostate cancer management in African men is 
quite challenging as most patients present with 
metastatic disease (Shenoy et al. 2016). 

Evidence-based medicine is a crucial tool in making 
clinical decisions and developing guidelines for 
management. (Burns, Rohrich, and Chung, 2011) Most 
screening and treatment guidelines used in different 
parts of the world for managing prostate cancer are 
formulated from evidence-based results obtained 

from mostly clinical trials and metanalyses on studies 
conducted in those countries. The National Institute 
for Health and Care Excellence (NICE) guidelines for 
treatment is predominantly based on research carried 
out in the United Kingdom (UK). A similar situation 
pertains regarding the National Comprehensive 
Cancer Network (NCCN) guidelines in the United 
States of America (USA). Evidence based medicine is a 
concept developed in the early 80s, then further 
described and modified by Sackett in 1989 (Sackett et 
al., 1996). It groups different studies based on their 
levels of evidence from one to five. Randomized 
controlled trials (RCT) and metanalyses are placed at 
the highest level of evidence, whilst, case series, case 
studies and expert opinions are at the lowest level. 
RCTs are structured to be unbiased; subjects are 
allocated randomly to two or more treatment groups 
whilst case series or expert opinion are associated with 
bias and based on writer’s experience or opinions and 
there is often no control of confounding factors. The 
centre for evidence-based medicine in Oxford 
developed an adaptable tool to assess the levels of 
evidence in 2011 (Table 1). The tool is a hierarchical 
system of classifying based on evidence and designed 
for use by researchers. 

Table 1: The Centre for Evidence-Based Medicine in Oxford published the levels of evidence in 2009, and 
modified in 2011(OCEBM Levels of Evidence Working Group et al. 2011) 

 



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd                   e3                                              Cancer Health Disparities 

RESEARCH 

In Nigeria, prostate cancer prevention, screening, 
and clinical treatment modalities should be based 
on evidence-based research done or validated in 
Nigerian patients, in the expectation that this 
would lead to improved treatment outcomes and 
therefore survival. However, there are no 
publications exploring the levels of evidence in 
prostate cancer research in Nigeria. This review 
was done to explore levels of evidence on prostate 
cancer in Nigeria. 

METHODS 

We followed the Preferred Reporting for 
Systematic Reviews and Meta-Analyses (PRISMA) 
statement for the conduct of our systematic 
review (except that we did not consider 
metanalyses). 

 

 

Figure 1: Illustrating the PRISMA selection criteria 

STUDY SELECTION An electronic literature search of all research 
published on prostate cancer from January 1975 to 



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd                   e4                                              Cancer Health Disparities 

RESEARCH 

May 2018 in Nigeria was conducted. We reviewed 
all articles found on PubMed, Web of Science, 
Embase, and Google Scholar search engines by 
searching “Prostate cancer in Nigeria”. Using the 
PRISMA and National Institute of Health (NIH) 
guidelines, we reviewed and classified the articles 
based on their study designs into different levels of 
evidence. We included all studies on prostate 
cancer in Nigeria with either the full article or 
abstract having adequate information on the 
methodology of the study and excluded those 
with insufficient details. Information extracted from 
studies include the year of publications, study 
design, and level of evidence. Studies selected 
were grouped into five levels of evidence 
according to the Oxford Centre for Evidence-
based Medicine classification (OCEBM Levels of 
Evidence Working Group et al. 2011). Meta-

analyses were not considered in the review due to 
varying study designs and difficulty in pooling 
them together. 

EVIDENCE SYNTHESIS 

During our search we identified 302 publications, 
106 duplicates were removed and 25 were 
excluded based on inadequate information on the 
methodology of the study. A total of 171 articles 
were eligible for this review. Most studies 
published were cross sectional studies (56%), 
followed by cohort studies (15%), laboratory 
studies(13% ), case reports (7%), expert opinion 
(3%), systematic reviews (2%) and meta-analysis 
(1%). There were no clinical trials on prostate 
cancer in Nigeria seen or registered on 
clinicaltrials.gov or other clinical trials registries 
(figure 2). 

 

Figure 2: Types of study designs on prostate cancer in Nigeria 

Based on Levels of Evidence, most studies (66%), 
were at level 4a of evidence (figure 3). These include 
case reports, case series, and cross-sectional studies. 
Seventeen percent of studies were at the level 5a 

evidence levels, including laboratory studies and 
expert opinion. Nine percent of the studies were at 
level 2b of evidence, which included cohort studies, 
5% at level 3b of evidence including case- control 

1

3

0

0

25

8

95

12

5

22

META-ANALYSIS

SYSTEMATIC REVIEWS

RANDOMISED CLINICAL TRIALS

NON RANDOMISED CLINICAL TRIALS

COHORT STUDIES

CASE-CONTROL STUDIES

CROSS-SECTIONAL STUDIES

CASE REPORTS/ CASE SERIES

BACKGROUND INFORMATION/EXPERT OPINION

ANIMAL RESEARCH/LAB STUDIES

Types of Study designs



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd                   e5                                              Cancer Health Disparities 

RESEARCH 

studies, whilst levels 2c and 2a constituted 2% and 
1% respectively. There were no studies at level 1 (a, b 
or c) of evidence (systematic reviews with 
homogeneity of randomised clinical trials, individual 
randomised clinical trials and all or none studies). 

 

 

 

 

 

 

Figure 3: Levels of evidence on prostate cancer research in Nigeria 

Most studies were published in 2017 (29 
publications were identified that year), followed by 

2012, 18 publications, 2013, 2014 and 2015 had 11, 
12 & 13 publications respectively (figure 4). 

0

20

40

60

80

100

120

1A 1B 1C 2A 2B 2C 3A 3B 4A 5A

Levels of Evidence on Prostate Cancer



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd                   e6                                              Cancer Health Disparities 

RESEARCH 

 

Figure 4: Showing number of publications per year 

DISCUSSION 

This study demonstrates the paucity of high level 
evidence research in prostate cancer in Nigeria. It 
showed that the commonest study design in 
prostate cancer research conducted in Nigeria is 
the cross-sectional study. Although, this design 
can rapidly generate data on some health-related 
events, it may however be plagued with different 
types of bias (Sedgwick 2014). Cross sectional 
studies can be used to generate a hypothesis and 
establish an association but not causation. Most 
researchers in Nigeria adopt this methodology 
because cross sectional studies are relatively cheap 
and easy to conduct, especially in a low-resource 

environment where the financial and personnel 
costs are lower than that required for higher level 
and more informative studies. There are very 
limited funding avenues available for research in 
Nigeria. Studies at higher levels of evidence, like 
clinical trials, are more rigorous, require higher 
levels of expertise and are capital intensive. 
However the benefits of this type of study remain 
numerous, including their ability to establish 
causation, assess impact of an intervention and 
develop treatment guidelines to improve 
treatment outcomes and survival. (Christensen et 
al. 2007) 

0

5

10

15

20

25

30

35

1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 2018

YEAR OF PUBLICATION 



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd                   e7                                              Cancer Health Disparities 

RESEARCH 

In Nigeria, there are limited efforts to foster high 
level biomedical research. These efforts are often 
led by established consortia focused on specific 
research goals. For example, the Prostate Cancer 
Transatlantic Consortium (CaPTC), established in 
2005, has supported prostate cancer research in 
Nigeria since 2006 (https://epi.grants.cancer.gov/ 
captc/) . CaPTC is a National Cancer Institute (NCI) 
Epidemiology and Genomics Research Program 
(EGRP) supported consortium. CaPTC has over 150 
members who are prostate scientists, clinicians, 
and consumer advocates from countries 
connected by the Transatlantic Slave Trade, 
including North America, Europe, the Caribbean, 
and Africa countries. CaPTC investigators 
collaborate on projects based on the following 
scientific aims: 

1. Explore and quantify the magnitude of 
prostate cancer morbidity and mortality 
variance among Black men of African ancestry; 

2. Explore genetic, environmental and behavioral 
etiology of this variance; and 

3. Develop community-sensitive initiatives to 
control prostate cancer globally. 

The official scientific conference for the CaPTC is 
the Biennial Science of Global Prostate Cancer 
Conference for Black men, which was held in 
Jacksonville (USA) in 2010, Nassau (Bahamas) in 
2012, Montego Bay (Jamaica) in 2014, Orlando 
(USA) in 2016, and will be held in Ilorin (Nigeria) in 
2018. Other active consortia in Nigeria are the 
African colorectal cancer Group (ARGO), The Men 
of African Descent and Carcinoma of the Prostate 
(MADCaP), and Breast Cancer Consortium. 

The commonest level of evidence of prostate 
cancer in this review is level 4, which includes: the 
case reports, case series, and cross-sectional 
studies. These levels of evidence are relatively low 

and are less likely to be adopted in developing 
treatment guidelines. Most international treatment 
guidelines are developed based on level 1 
evidence, clinical trials. They analyse results from 
these clinical trials conducted on prostate cancer 
patients in their countries and then adapt them in 
the development of treatment guidelines. An 
example is the STAMPEDE trial in the UK (James et 
al. 2015) which has led to changes in the standard 
of care of prostate cancer patients in the UK 
Another is the CHATTERED trial (Sweeney et al. 
2015), a similar clinical trial as the STAMPEDE, 
which was conducted in the USA. Clinical trials 
have always sharpened the paradigms of 
treatment internationally. 

The study showed a steep increase in publications 
on prostate cancer in Nigeria from the year 2000 
to date. Despite this increase the proportion 
remains very low when compared to prostate 
cancer studies in other countries. The highest 
number of publications was published in 2017, 
when a total of 29 articles were published on 
prostate cancer. When compared with other parts 
of the world, the USA and UK uniquely had over 
300 publications on prostate cancer on PubMed 
search engine in 2017. 

A major reason for low levels of prostate cancer 
research in Nigeria is the low funding available for 
cancer research from public and private 
agencies/organizations. A major funding channel 
for research in Nigeria is the Tertiary Education 
Trust Fund (TETFund) established under the 
TETFund Act (Tertiary Education Trust Fund) in 
2011. TETFund gets the funding by imposing a 2% 
education tax on all registered companies in 
Nigeria. The fund is disbursed to tertiary 
educational institutions at Federal and State levels 
as research grants in all fields (TETFund 2014). 



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd                   e8                                              Cancer Health Disparities 

RESEARCH 

However, the rising trend of cancers in Nigeria 
necessitates an increase in cancer research funding 
as exemplified by developed countries. Developed 
countries have several funding channels for 
research. These include Government funding and, 
Non-governmental organisations and charities. In 
the United States, the 2017 Budget allocated $33.1 
billion (0.8%), out of the $4.2 trillion to the 
National Institute of Health to accelerate ground-
breaking research on cancer, precision medicine 
and others (Sargent et al. 2017). In the UK, the total 
investment is £26.3 billion between 2016/17 to 
2020/21 with an average of £5 billion pounds 
yearly as allocations for the science and research 
in the budget (HM Government 2016). It is 
therefore not surprising that prostate cancer 
survival has improved in both United States and 
UK. To make significant leap in fighting prostate 
cancer in Nigeria, there needs to be focus on 
funding prostate cancer research. While it will 
greatly help to have governmental funding, 
corporate and philanthropic giving will also be 
very important. In September 2005, the 
Foundation for Carcinoma of the Prostate 
Transatlantic Research was established to 
accelerate prostate cancer research in Nigeria. This 
foundation is a step in the right way to raise the 
profile of prostate cancer research in Nigeria. 

CONCLUSION 

Prostate cancer research is currently at low levels 
of evidence in Nigeria. As stated by Prof. Folakemi 
Odedina, “Actionable research is key to defeating 
prostate cancer” (Nigerian Guardian, July 8, 2017). 
Prostate cancer researchers should make efforts to 
conduct and publish more studies especially at 
higher levels of proof like RCTs and 
metanalysis/systematic reviews of RCT as well as 
develop treatment guidelines for patients based 

on these higher levels of evidence. It is also 
pertinent that the Nigerian Government increases 
its efforts in providing the support needed on 
funding cancer-related research. The Nigerian 
Government should also develop and implement 
policies related to increasing cancer research 
funding through governmental grants. Finally, 
there needs to be increase in corporate funding 
and philanthropic funding for prostate cancer 
research. 

Acknowledgements 
We acknowledge Ms. Kimberly Meza for her 
editorial review 

Conflict of interest 
The authors declare that no competing or conflict of 
interests exists. The funders had no role in study 
design, writing of the manuscript, or decision to 
publish. 

Authors’ contributions 
O.A.F, A.C.S & F.B did the manuscript writing and 
design. O.I, O.O, A.A did the data extraction and 
literature search. F.C, N.D, F.O supervised the project. 
 
REFERENCES 
Adeloye, Davies, Rotimi Adedeji David, Adewale Victor 

Aderemi, Alexander Iseolorunkanmi, Ayo Oyedokun, 
Emeka E.J. Iweala, Nicholas Omoregbe, and Charles K. 
Ayo. 2016. ‘An Estimate of the Incidence of Prostate 
Cancer in Africa: A Systematic Review and Meta-Analysis’. 
PLoS ONE 11 (4). https://doi.org/10.1371/journal.pone. 
0153496. 

Brawley, Otis W. 2012. ‘Trends in Prostate Cancer in the 
United States’. Journal of the National Cancer Institute - 
Monographs, no. 45: 152–56. https://doi.org/10.1093/ 
jncimonographs/lgs035. 

Burns, Patricia B., Rod J. Rohrich, and Kevin C. Chung. 2011. 
‘The Levels of Evidence and Their Role in Evidence-Based 
Medicine’. Plastic and Reconstructive Surgery 128 (1): 305–
10. https://doi.org/10.1097/PRS.0b013e318219c171. 

Christensen, Michael C, Alan Moskowitz, Ardesheer Talati, 
Richard R Nelson, and Nathan Rosenberg. 2007. ‘On the 
Role of Randomized Clinical Trials in Medicine’. 



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd                   e9                                              Cancer Health Disparities 

RESEARCH 

Economics of Innovation and New Technology 16 (5): 357–
70. https://doi.org/10.1080/10438590600982426. 

Elima, Maria Paula Curado, Olufemi Ogunbiyi, Emmanuel 
Oga, Toyin Fabowale, Festus Igbinoba, Gloria Osubor, et 
al. 2012. ‘Cancer Incidence in Nigeria: A Report from 
Population-Based Cancer Registries.’ Cancer 
Epidemiology 36 (5). NIH Public Access: e271-8. 
https://doi.org/10.1016/j.canep.2012.04.007. 

Ferlay, Jacques, Isabelle Soerjomataram, Rajesh Dikshit, Sultan 
Eser, Colin Mathers, Marise Rebelo, Donald Maxwell 
Parkin, David Forman, and Freddie Bray. 2015. ‘Cancer 
Incidence and Mortality Worldwide : Sources , Methods 
and Major Patterns in GLOBOCAN 2012’. Int J Cancer 386 
(136 (5)): 359–86. https://doi.org/10.1002/ijc.29210. 

HM Government. 2016. ‘The Allocation of Science and 
Research Funding’. Gov.Uk, no. March: 1–57. 

James, Nicholas David, Matthew Robert Sydes, Malcolm David 
Mason, Noel W Clarke, David Paul Dearnaley, Melissa 
Ruth Spears, Robin Millman, et al. 2015. ‘Docetaxel 
and/or Zoledronic Acid for Hormone-Naïve Prostate 
Cancer: First Overall Survival Results from STAMPEDE 
(NCT00268476).’ J Clin Oncol 33. 

OCEBM Levels of Evidence Working Group, OCEBM, Jeremy 
Howick, Iain Chalmers (James Lind Library), Paul Glasziou, 
Trish Greenhalgh, Carl Heneghan, Alessandro Liberati, et 
al. 2011. ‘The Oxford Levels of Evidence 2’. Oxford Centre 
for Evidence-Based Medicine 1 (version): 5653. 

Odedina, Folakemi T., Titilola O. Akinremi, Frank 
Chinegwundoh, Robin Roberts, Daohai Yu, R. Renee 
Reams, Matthew L. Freedman, Brian Rivers, B. Lee Green, 
and Nagi Kumar. 2009. ‘Prostate Cancer Disparities in 
Black Men of African Descent: A Comparative Literature 
Review of Prostate Cancer Burden among Black Men in 
the United States, Caribbean, United Kingdom, and West 
Africa’. In Infectious Agents and Cancer. Vol. 4. 
https://doi.org/10.1186/1750-9378-4-S1-S2. 

Sackett, D., W. Rosenberg, J. Gray, R. Haynes, and W. 
Richardson. 1996. ‘Evidence Based Medicine: What It Is 
and What It Isn’t’. BMJ 312: 71–72. https://doi.org/ 
10.1136/bmj.312.7023.71. 

Sargent, John F, Judith A Johnson, Jim Monke, Daniel Morgan, 
and Harold F Upton. 2017. ‘Federal Research and 
Development Funding: FY2017 Specialist in Biomedical 
Policy Specialist in Agricultural Policy Analyst in Natural 
Resources Policy’. 

Sedgwick, Philip. 2014. ‘Cross Sectional Studies: Advantages 
and Disadvantages’. BMJ (Online). https://doi.org/ 
10.1136/bmj.g2276. 

Shenoy, Divya, Satyaseelan Packianathan, Allen M. Chen, and 
Srinivasan Vijayakumar. 2016. ‘Do African-American Men 
Need Separate Prostate Cancer Screening Guidelines?’ 
BMC Urology 16 (1). https://doi.org/10.1186/s12894-016-
0137-7. 

Sweeney, Christopher J., Yu-Hui Chen, Michael Carducci, 
Glenn Liu, David F. Jarrard, Mario Eisenberger, Yu-Ning 
Wong, et al. 2015. ‘Chemohormonal Therapy in 
Metastatic Hormone-Sensitive Prostate Cancer’. New 
England Journal of Medicine 373 (8): 737–46. 
https://doi.org/10.1056/NEJMoa1503747. 

TETFund. 2014. ‘GUIDELINE FOR ACCESSING TETFund 
NATIONAL RESEARCH FUND TERTIARY EDUCATION 
TRUST FUND ( TETFund ) Publication’, 1–53. 

 
 
 
 


