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Risk factors for prostate cancer in West 
African Men: The Familial Cohort Study 
Catherine A. Oladoyinbo 1,7*, Oluwafunke O. Akinbule1,7, Opeyemi O. Bolajoko 1,7, Justice Moses K. Aheto2,7, 
Getachew Dagne 3,7 , Faruk Mohamed 4,7, Iya Eze Bassey5,7, Folakemi T. Odedina6,7, Ruth Agaba 7, Nissa 
Askins 6,7, Olubanke O. Ogunlana8,7, Motolani E. Ogunsanya 9,7, Aishat M. Suleiman 4,7, Stanley O. Anyanwu 

5,7, Rebecca M. Gali 10,7, Ernest Kaninjing 11,7, Blaise Nkegoum 12,7, Abidemi Omonisi13,7, Anthonia C. Sowunmi 
14,7, Paul Jibrin 15,7, Emeka E. Iweala8,7, Omolara A. Fatiregun16,7 and Ademola A. Popoola17,7 

 

Authors’ Affiliations: 
1Federal University of Agriculture, Abeokuta, Ogun State, Nigeria 
2Department of Biostatistics, University of Ghana, Accra 
3University of South Florida, USA 
4Ahmadu Bello University, Zaria, Nigeria 
5DUniversity of Calabar, Calabar, Nigeria 
6University of Florida, Lake Nona Campus, FL, USA 
7Prostate Cancer Transatlantic Consortium (CaPTC) 
8Covenant University, Ota, Nigeria 
9University of Oklahoma Health Sciences Center, Oklahoma City, OK 73117, USA 
10University of Maiduguri, Maiduguri, Nigeria 
11Georgia College & State University, USA 
12University Hospital Center, Yaounde, Cameroon 
13Ekiti State University, Nigeria 
14Lagos University Teaching Hospital 
15National Hospital, Abuja, Nigeria 
16Lagos State University Colege Medicine, Nigeria 
17University of Ilorin Teaching Hospital, Ilorin, Nigeria 

*Corresponding author: Oladoyinbo Catherine A,  
Email:oladoyinboca@funaab.edu.ng  
 

 

 

mailto:oladoyinboca@funaab.edu.ng


 
 
 
 
 

 
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ABSTRACT 
Prostate cancer (CaP) has been identified as the most common cancer among men globally with higher 
prevalence, incidence and mortality rates in Black men. This study aims to assess the risk factors for CaP 
among West African men residing in Nigeria, Cameroon and the United States. A validated Prostate 
Cancer Transatlantic Consortium (CaPTC) familial cohort study questionnaire was used to collect data 
on the respondents’ characteristics, alcohol consumption pattern, smoking pattern, knowledge of CaP, 
physical activity level and cancer status. Anthropometric measurements were taken using standard 
procedures. Data was summarised using descriptive statistics and penalized maximum likelihood logistic 
regression analysis via Firth method to determine the association between CaP status and independent 
variables. The results show that 2.21% of the respondents reported to have been diagnosed with CaP. 
The median age of the respondents was 47 years with 62.21% having poor knowledge of CaP, and 
17.11% with central obesity. More than half (62.07%) of the respondents currently drink alcohol, 24.4% 
are current smokers and 51.5% engage in low physical activity. Number of daughters (OR=1.2435, 
95%CI: 1.0045, 1.5393), consistent alcohol drinkers in years (OR=1.0484, 95%CI: 1.0151, 1.0829) and 
glasses of drink on a typical occasion (OR=1.2145, 95%CI: 1.0560, 1.3968) were associated with CaP 
status. In the multiple logistic regression, only number of daughters (OR=1.2531, 95%CI: 1.0055, 1.5617) 
was associated with CaP status. In conclusion, poor knowledge of CaP was observed among the 
respondents. Alcohol consumption, increased number of glasses of alcohol consumed on typical 
occasion and increasing number of daughters were associated with CaP status and increased risk of the 
disease. 

KEYWORDS: Prostate cancer, West Africa, obesity, daughters, alcohol consumption 

Citation: Oladoyinbo et al (2019) Risk factors for prostate cancer in West African Men: The Familial Cohort 
Study. 4: e1-e11. doi:10.9777/chd.2019.1007 
 
 



 
 
 
 
 

 
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Introduction 

Prostate cancer is the most frequently diagnosed 
cancer in men. It occurs as a result of genetic 
mutations or changes of the gene’s blueprint of 
the prostate cell causing the normal prostate cells 
to divide too quickly or die too slowly (Odedina et 
al, 2016). Black Africans have 70% higher risk of 
developing Prostate Cancer (CaP) when compared 
to non-Hispanic whites and 137% higher death 
rates (American Cancer Society, 2016). Findings 
have shown that African Americans living in the US 
have 1.6 times risk of developing CaP when 
compared to Caucasian men (Al Olama et al, 2014; 
American Cancer Society, 2016). 

Prostate cancer has been reported to be the 
second leading cause of cancer death in men, 
both in developed and developing countries, with 
an estimate of 180,890 new cases and 26,120 
cancer death in the United States in 2016 
(American Cancer Society, 2016). The burden of 
CaP is projected to rise, with over 75 million 
prevalent cases, 27 million incident cases and 17 
million cancer deaths globally by 2030 (Parkin et 
al, 2003; Ferlay et al, 2010). 

The higher incidence and prevalence of CaP in 
Black African and African American compared to 
other races in the world has increased rate of 
morbidity and mortality among these populations 
(Odedina et al, 2006; Delongchamps et al, 2007; 
Odedina et al, 2009; Akinremi et al, 2010; Rebbeck 
et al, 2013). 

The known risk factors for developing CaP include: 
increasing age, African ancestry, family history and 
certain inherited genetic conditions. Other 
modifiable risk factors include tobacco use, alcohol 
consumption, increased body weight, central 
obesity, poor nutrition, physical inactivity, poor 

knowledge levels and certain infectious agents. 
These factors also play major roles in the 
development of CaP (IHME: 2013; Jacobs et al, 
2015; World Cancer Research Fund, 2015). 

Findings have linked genetic susceptibility of CaP 
to African heritage and familial disease (IARC, 
2014; American Cancer Society, 2016). Also, there 
are strong evidences that increased body mass 
index and central obesity increases the risk of CaP 
incidence and mortality (Maclnnis et al, 2003; 
Gong et al, 2006; Pischon et al, 2008; Martin et al, 
2009; Stocks et al, 2010; Batty et al, 2011; Dehal et 
al, 2011; Discacciati et al, 2011; Shafique et al, 2012). 

Alcohol consumption and smoking have also been 
implicated with the risk of developing CaP 
(Sawada et al, 2014) and reduced smoking have 
been associated with a decline in CaP mortality 
rates (Jones et al, 2016). 

Studies on risk factors for CaP in West African 
countries are scarce. Since Nigeria is an ancestral 
home of many Black men living in the diaspora, 
studies involving Black men from Nigeria and 
other West African countries may provide 
information on some of the risk factors 
predisposing Black men to CaP. This study 
therefore aims to assess the risk factors for CaP in 
West African Black men. 

Methodology 

This study was a cross-sectional study of West 
African Black men residing in Nigeria, Cameroon 
and the United States. Data were collected from 
ten (10) CaPTC sites across the six (6) geo-
political zones in Nigeria, one site from 
Cameroon and one site from the USA. 
Respondents within the age range of 35 to 75 
years, who were willing to participate in the 



 
 
 
 
 

 
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study and duly signed the informed consent 
were recruited. A validated CaPTC familial 
project study questionnaire was used to collect 
data on the respondents’ characteristics, alcohol 
consumption and smoking patterns, knowledge 
of CaP (causes, prevention, screening test, signs 
and symptoms), physical activity level and self-
reported cancer status. Anthropometric 
measurements (height, weight and waist 
circumference) were taken using the appropriate 
equipment. Body mass index and central obesity 
were calculated from the anthropometric 
measurements. Knowledge of CaP was assessed 
from twenty (20) questions. Every correct answer 
was scored as 1 and incorrect answers were 
scored as 0. Individual total knowledge score 
was derived by summing all the scores. The 
individual score was divided by the maximum 
score (20) and multiplied by 100 to convert it to 
percentage. The percentage values were then 
categorized into poor (0 – 40%), moderate (41 – 
69%) and adequate (≥70%) knowledge. Data 
were summarised using frequencies and 
percentages for categorical variables while 
median and interquartile range (upper quartile – 
lower quartile) were used to summarise the 
continuous variables. We applied penalized 
maximum likelihood logistic regression analysis 
via Firth method to determine the association 
between CaP status and independent variables. 
In the regression analysis, only 470 out of the 
498 respondents were included due to missing 
observations in some risk factors considered in 
the model. In addition, several important risk 

factors could not be included in the model due 
to missing data which could lead to removal of 
respondents who reported to have been 
diagnosed of CaP. Not removing such risk 
factors could have led to a reduced data pool, 
especially for those with a positive diagnosis of 
CaP. To reduce bias in maximum likelihood 
estimates due to small number of cancer cases 
in the data, we applied penalized maximum 
likelihood logistic regression analysis via Firth 
method (Firth, 1993; Heinze and Schemper, 
2002) to examine risk factors for cancer status 
among the respondents. Firth method is also 
used to address the problem of separation in 
logistic regression (Heinze and Schemper, 2002). 

Results 

Characteristics of the respondents 
A total of 498 men participated in the study out of 
which 11 (2.21%) respondents reported to have 
been diagnosed with CaP. Among those who 
reported to have been diagnosed of CaP, 10 
(90.91%) reside in Nigeria and only 1 (9.09%) 
resides in Cameroon. The median age of 
participants is 47 years with an interquartile range 
(IQR) of 15 years. The median age at first drink of 
alcohol was 20 years with an interquartile range of 
7 years. The median number of years respondents 
consistently drank alcohol was 20 years (IQR = 23) 
and the glasses of drink consumed on a typical 
occasion among respondents was 3 (IQR = 2). A 
total of 443 respondents (92.48%) of the 
respondent were married while 408 (85.18%) of 
the respondents reside in Nigeria (Table 1). 

 

 

 



 
 
 
 
 

 
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Table 1: Respondents’ characteristics. 
Characteristics Median (LQ-UQ) 

Age (n = 478) 47 (40-55) 
Number of brothers (n = 479) 3 (2-5) 
Number of sisters (n = 460) 3 (2-5) 
Number of daughters (n = 474) 2 (1-3) 
Number of sons (n = 478) 2 (1-3) 
Age at first drink of alcohol in years (n = 480) 20 (17-24) 
Consistent alcohol drinkers in years (n = 480) 15 (5-28) 
Glasses of drink on typical occasion (n = 480) 3 (2-4) 
Self-reported Cancer status(n=498)   

Yes n=11 2.21% 
No n=487 97.79% 

Marital status (n= 479)   
Married n = 443 92.48% 
Not married n = 36 7.52% 

Country (479)   
Cameroon n=27 5.64% 
Nigeria n=408 85.18% 
USA n=44 9.18% 

LQ: Lower quartile. UQ: Upper quartile. n: number of observations 
Consistent alcohol drinkers: drank alcohol at least once a week for at least 6 months in years 
 

 

Figure 1 Histogram showing the age distribution of respondents. 



 
 
 
 
 

 
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Modifiable risk factors for prostate cancer among 
respondents 
Table 2 shows the description of the modifiable 
risk factors for prostate cancer among the 
respondents. More than half (62.21%) of the 
respondents had poor knowledge, 27.81% had 
moderate knowledge and 9.98% had good 
knowledge of CaP. 

A quarter of the respondents were overweight, 
20.9% were obese and 17.1% had central obesity. 
About 20.4% of the respondents smoke and 79.6% 
have never smoked. Among the smokers, 24.44% 

are current smokers while 75.56% had smoked at 
one time or the other in their lifetime. About 
55.65% respondents drink alcohol while 44.35% 
never drank. Among the alcohol drinkers, 62.07% 
currently drink alcohol while 37.93% had drank 
alcohol at one time or the other in their lifetime. 
About half (51.59%) of the respondents engage in 
low physical activity. 

 

 
Table 2: Modifiable risk factors for prostate cancer among respondents. 

Modifiable risk factors Frequency Percentage  
Knowledge of CaP (n=471) 

Poor 
Moderate 
Adequate 

 
293 
131 
47 

 
62.21 
27.81 
9.98 

Body mass index (n=345) 
Underweight 
Normal weight 
Overweight 
Obesity 

 
69 
112 
92 
72 

 
20.0 
32.46 
26.67 
20.87 

Central Obesity (n=480) 
Yes 
No 

 
82 
398 

 
17.08 
82.92 

Physical activity (n=471) 
Low 
Moderate 
High 

 
243 
77 
151 

 
51.59 
16.35 
32.06 

Smoking status (n=442) 
smokers 
Non-smokers 

 
90 
352 

 
20.36 
79.64 

Smokers (n=99) 
Current smokers 
Smoked in a lifetime 

 
22 
68 

 
24.44 
75.56 

Breathe in smoke in the past seven days (n= 480) 
None 
One day 
Two or more days 
Don’t know / Refused to answer 

 
306 
18 
26 
130 

 
63.75 
3.75 
5.42 
27.08 

Number of days/week tobacco smoke was inhaled (n=480) 
None 
One day 

 
332 
5 

 
69.17 
1.04 



 
 
 
 
 

 
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Two or more days 
Don’t know / Refused to answer 

13 
130 

2.71 
27.08 

Alcohol drinking Status (n=469) 
drinkers 
Non-drinkers 

 
261 
208 

 
55.65 
44.35 

Alcohol drinkers (n=261) 
Current drinkers 
Drank in a lifetime 

 
162 
99 

 
62.07 
37.93 

CaP- prostate cancer 
Smoking in this context is defined as tobacco smoking 

Factors associated with prostate cancer status and 
risk 
Presented in Table 3 are the results from the 
penalized maximum likelihood logistic regression 
analysis. In the univariate logistic model, the 
variables, number of daughters (OR=1.2435, 
95%CI: 1.0045, 1.5393), consistent alcohol drinkers 
in years (OR=1.0484, 95%CI: 1.0151, 1.0829) and 
glasses of drink on a typical occasion (OR=1.2145, 
95%CI: 1.0560, 1.3968) were associated with CaP 
status. Increase in number of daughters, consistent 

alcohol drinkers in years, and glasses of drink on a 
typical occasion were associated with increased 
risk of CaP in men. Age, marital status, number of 
brothers and sisters, number of sons, age at first 
drink were not associated with CaP status. In the 
multiple logistic regression, only number of 
daughters (OR=1.2531, 95%CI: 1.0055, 1.5617) was 
associated with CaP status. Likelihood of 
developing CaP increases with increasing number 
of daughters. 

Table 3: Factors associated with Prostate cancer status among men (n=470). 
 Univariate logistic model Multiple logistic model 

Characteristics UOR 95% CI AOR 95% CI 

Socio-demographic factors 
Age 0.9987 (0.9412, 1.0597) 0.9997 (0.9401, 1.063) 

Marital status 
Married Ref    

Not married 1.7364 (0.3034, 9.9395)   
Number of brothers 1.1126 (0.9258, 1.337)   

Number of sisters 1.0755 (0.8692, 1.3308)   
Number of daughters 1.2435* (1.0045, 1.5393) 1.2531* (1.0055, 1.5617) 

Number of sons 1.1888 (0.9486, 1.4898)   
Drinking Habits 

Age at first drink 0.9815 (0.9283, 1.0377)   
Consistent alcohol drinkers (years) 1.0484** (1.0151, 1.0829) 1.0394 (0.9983, 1.0823) 

Glasses of drink on typical occasion 1.2145** (1.056, 1.3968) 1.0715 (0.8841, 1.2986) 



 
 
 
 
 

 
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UOR: unadjusted odds ratio. AOR: adjusted odds ratio. CI: confidence interval. *: p<0.05, ref: reference 
category 

Discussion 

This study assessed the risk factors for prostate 
cancer in West African men in the CaPTC familial 
cohort study. 

Previous findings revealed a high prevalence of 
CaP in Black African men (Odedina et al, 2006; 
Delongchamps et al, 2007; Odedina et al, 2009; 
Akinremi et al, 2010; Rebbeck et al, 2013). In this 
study, the number of respondents who reported 
to have been diagnosed with CaP out of the 498 
was 2.21%, relatively lower. Other respondents 
who reported not to have been diagnosed with 
CaP may not have undergone any CaP screening 
test. Studies have revealed poor screening 
behaviour among West African men, particularly 
Nigerian men (Agbuguiet al, 2013; Ogundele and 
Ikuerowo, 2015). This might have contributed to 
the under-reporting of CaP cases. Poor screening 
behaviour of respondents towards CaP may lead 
to high prevalence of advanced stage of CaP 
which is prevalent in CaP management in Nigeria 
and hence reduce the rate of surviving the disease. 

Most of the respondents had poor knowledge on 
CaP and only one-tenth had adequate knowledge. 
Few studies conducted in some Nigerian states 
revealed a low level of awareness and knowledge 
of CaP risk factors and symptoms (Ukoli et al, 
2003; Oladimeji et al, 2010; Ajape et al, 2010; 
Ogundele and Ikuerowo, 2015). Adequate 
knowledge on CaP may promote early detection, 
prevent CaP progression into the advanced stage 
as well as the rate of morbidity and mortality 
associated with CaP (Ogunbiyi, 2011; Akinremi et 
al, 2014). Poor knowledge among respondents in 

this study may put them at risk of developing CaP 
or having an advanced stage of CaP. 

The prevalence of overweight, obesity and central 
obesity was high among the respondents. 
Overweight and obesity have been reported to be 
associated with increased risk of CaP (Stocks et al, 
2010; Batty et al, 2011; Dehal et al, 2011; Discacciati 
et al, 2011;; Basset et al, 2012; Shafique et al, 2012). 
Obesity has been reported to influence the levels 
of some hormones and growth factors including 
insulin and leptin and thereby stimulates the 
growth of cancer cells (Platz et al, 2005). Obesity, 
particularly central obesity has been reported to 
increase the risk of advanced CaP (Maclnnis et al, 
2003; Gong et al, 2006; Pischon et al, 2008; Martin 
et al, 2009). This is due to its lowering effect on 
serum testosterone levels. Testosterone plays an 
important role in determining the differentiation 
status of the prostate epithelium. Therefore, low 
levels of testosterone may increase the growth of a 
less differentiated, destructive CaP phenotype (De 
Pergola and Silvestris, 2013). 

This study revealed that about one in five of the 
respondents smoke and more than half consume 
alcohol. Studies have revealed that smoking, 
number of packs smoked, years of smoking and 
alcohol consumption increase the risk of developing 
CaP, as well as advanced CaP and death from CaP 
(Huncharek et al, 2010; Rolison et al, 2012; ; Sawada 
et al, 2014; Nunzio et al, 2015). Also, a study 
conducted in the US revealed that smokers are less 
likely to undergo CaP screening and less likely to 
screen frequently (Rolison et al, 2012). 

This study showed that increasing number of 
daughters was associated with increased odds of 
developing CaP. An earlier study carried out 



 
 
 
 
 

 
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among the Jerusalem perinatal cohort study by 
Harlap et al., (2007), found that Israeli men who 
developed CaP have an impaired ability to 
reproduce male children. The Y-chromosome has 
been implicated in the onset of prostate cancer in 
men (Krausz et al., 2004) and has been suggested 
to harbour CaP risk (Harlap et al., 2007). However, 
another study in the US reported that men who 
were unable to give birth to male children had a 
lower risk of CaP (Spatz, et al., 2004; Eisenberg et 
al., 2011) submitting that prostate carcinogenesis 
may be linked to the X chromosomes. Given these 
mixed findings, more studies are needed to clearly 
understand the role of fatherhood and CaP status. 

Also, consistent alcohol consumption was found to 
increase the risk of CaP. Previous studies have 
established that consistency in alcohol 
consumption is associated with CaP( Rota et al., 
2012; Fowke et al., 2014; Demoury et al., 2016). This 
might be due to the metabolism of alcohol which 
releases acetaldehyde which has been suggested 
to be carcinogenic because it interferes with DNA 
replication (Seitz and Becker, 2007; Lachenmeier et 
al., 2012; Zhao et al., 2016). 

The current study also shows that CaP risk 
increases with the number of glasses of alcoholic 
drink consumed. Earlier studies have consistently 
shown that a higher volume of alcohol intake on a 
typical occasion is indeed associated with 
increased risk of CaP (Fowke et al., 2014; Demoury 
et al., 2016; Zhao et al., 2016). 

In conclusion, poor knowledge of the causes, 
screening test, signs and symptoms of CaP was 
observed among the respondents. Alcohol 
consumption, increased number of glasses of 
alcohol consumed on typical occasion and an 
increasing number of daughters were found to be 

associated with CaP status and increased risk of 
the disease. 

Acknowledgements 
Funding support for this project was provided by 
the prostate Cancer Transatlantic Consortium 
(CaPTC) 

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

Authors’ contributions 
All authors contributed to the study. From data 
collection, data entry and analysis, manuscript writing 
and editing. 

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