www.companyofscientists.com/index.php/chd e1 Cancer Health Disparities RESEARCH 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 www.companyofscientists.com/index.php/chd e2 Cancer Health Disparities RESEARCH 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 www.companyofscientists.com/index.php/chd e3 Cancer Health Disparities RESEARCH 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 www.companyofscientists.com/index.php/chd e4 Cancer Health Disparities RESEARCH 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). www.companyofscientists.com/index.php/chd e5 Cancer Health Disparities RESEARCH 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. www.companyofscientists.com/index.php/chd e6 Cancer Health Disparities RESEARCH 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 www.companyofscientists.com/index.php/chd e7 Cancer Health Disparities RESEARCH 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) www.companyofscientists.com/index.php/chd e8 Cancer Health Disparities RESEARCH 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 www.companyofscientists.com/index.php/chd e9 Cancer Health Disparities RESEARCH 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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