Current Breast Cancer Statistics and Scenarios in Africa

 
 

Current Breast Cancer Statistics and Scenarios in Africa

Dr Linda Agbugba and Dr Lopamudra Das Roy

Published 02/2023

@BreastCancerHub, All Rights Reserved

Abstract

Breast cancer is one of the leading causes of mortality in women globally. In Africa, breast cancer ranks as the most common cancer type in women. It is associated with several risk factors like lifestyle, genetic and environmental influences. The incidence and mortality rate of breast cancer in women varies across the Africa continent according to risk factor. Amongst the breast cancer subtypes, triple negative breast cancer (TNBC) is the most common among African women. Factors such as late presentation, lack of infrastructure for screening and therapeutic intervention, and lack of awareness have contributed to lower survival rate to breast cancer in Africa. The highest mortality and incidence rate reported for breast cancer was in the West Africa region. Although, there seems to be an under-reporting of the actual breast cancer burden in Africa. This review highlights breast cancer incidence rate, mortality rate, survival rate, risk factors, and tumor biology across various regions in Africa.

Keywords: Breast cancer, genetics, lifestyle, mortality rate, tumor biology

Introduction

Globally, cancer is one of the major non-communicable diseases of public health interest. Cancer is a leading cause of death in various continents of the world with an increasing incidence and mortality rate in Africa (Bahnassy et al., 2020; Hamdi et al., 2021; Sharma et al., 2022). The survival rate for black individuals has been reported to be lower when compared to white individuals for most cancer types (Siegel et al., 2022). No organ of the body is exempted from undergoing malignant changes although some may be more prone than others in different sexes. Breast cancer is one of the commonest cancer types affecting women worldwide with multifaceted risk factors and heterogeneous clinical disease outcomes (Mousayi et al., 2007; Ferlay et al., 2015). Pfeiffer et al. (2018) attributed the gradual increase in the incidence rate of breast cancer in women from the mid-2000s to be partly due to declined fertility rate and body overweight. Earlier review report by Kesley et al. (1993) associated nulliparity to increased risk of having breast cancer after 40 years while multiple pregnancies carried to Full-term decreases the risk of breast cancer after 40 years.

Breast cancer burdens across different countries of the world are usually measured using estimates of age, age-standardized incidence and mortality ratios, mortality-incidence ratio (a useful proxy indicator of 5-year survival rate), a 5- year prevalence and human development index (HDI) (Sharma, 2020). This HDI is a summary measure of three developmental indicators: education (mean and expected years of schooling), income (gross national income per capita) and health (focus on life expectancy) (UNDP, 2018). Hu et al. (2016) analysis of GLOBOCAN 2012 report revealed that the breast cancer burden varies according to the human developmental status and health care system of countries. The need for more studies to know the exact effect of socioeconomic status and healthcare services on breast cancer outcomes was advocated for based on this retrospective analysis by Hu et al. (2016). The incidence and mortality rate of female breast cancer globally as reported by GLOBOCAN 2020 was 11.7% and 6.9%, respectively, higher than other estimated cancer types.

In Africa, breast cancer is the second cause of death in women. The report of GLOBOCAN 2018 showed that breast cancer represents 27.7% of the total cancer burden in African countries and is closely followed by cervical cancer with 19.6% representation of the total cancer cases (Bahnassy et al., 2020). GLOBOCAN 2020 reports that breast cancer is the most common cancer type in females in Africa with an average of 186,598 new cases and 85,787 deaths. Female breast cancer cases have risen in Africa due to certain risk factors associated with genetics, environmental influences and lifestyle changes such as marital delay, breastfeeding duration and menarche time of onset (Porter, 2008; Arnold et al., 2015; Sharma, 2016; Li et al., 2017). A 2002 collaborative study that evaluated 47 epidemiologic studies in 30 countries involving about 50,302 breast cancer cases and 96,973 controls discovered that there was a reduction in the relative risk for breast cancer in parous women by 4.3% and 7%, for every 12 months a woman breastfeeds and for each full-term birth, respectively.  Recent review report from United Kingdom revealed that breast feeding reduces the risk of breast cancer in BRCA1 mutation carriers (22-50%). This finding was attributed to changes in RNA processing and cellular differentiation associated with pregnancy (Stordal, 2022). Marital delay serves as a risk factor to breast cancer mostly because of its association with delayed age at first full term pregnancy. Early menarche has been reported to increase the risk of breast cancer due to early exposure of the mammary epithelium to estrogen (Clavel-Chapelon, 2002; Key et al., 2011; Willet et al., 2014).

Saberian et al. (2021) showed that the incidence rate of breast cancer per 100000 persons in 53 African countries rose from 18.3 to 24.6 from 1990 to 2016. While a report by Hamdi et al. (2021) showed that the fatality rate of breast cancer decreased from 2002 to 2008 and remained relatively constant from 2012 to 2018 in all African regions. According to Sharma (2020), the age-related incidence of breast cancer was high among persons 30 to 49 years while the mortality to incidence ratio (MIR) in Africa as of 2018 was 0.44.

Several factors such as late presentation, lack of infrastructure for screening and therapeutic intervention, and lack of awareness have contributed to the high mortality rate and lower survival rate (Allemani et al., 2018; Sharma, 2020). According to Abdulrahman and Rahman (2012), 50-75% of African women are presented with the advanced stage of breast cancer. Jedy-Agba et al. (2016) stated that advanced stage presentation is the major contributory factor to the breast cancer burden in Africa. The challenge of breast cancer screening in Africa is greatly dependent on a lack of financial aid, and inadequate well-trained technicians and radiologists (Corbex et al., 2012; Denny et al., 2017). Although mammography is the gold standard for breast cancer screening, but many times, mammograms may miss tumors due to the breast tissue density (Tsu et al., 2013).  

Many risk factors have been associated with an increase in breast cancer in Africa and they include use of contraceptives, obesity, lower parity, sedentary lifestyle, older age at first birth, reduction in breastfeeding duration, high-calorie diets, gene-environmental interactions and genetic predispositions (Joko-Fru et al., 2020). Nulliparity may be a risk factor for luminal-type breast cancer as pregnancy and breastfeeding may reduce the number of menstrual cycles, decreasing the hormone-associated risk of luminal-type breast cancer (Yang and Jacobsen, 2008; Lambertini et al., 2016; Anstey et al., 2017).  The pattern of breast cancer occurrence across Africa varies with countries according to the changing risk factors (Joko-Fru et al., 2020). Although genetic mutation has been implicated as a breast cancer risk factor, evidence to support this in Africa is limited due to genetic diversity and poor genetic testing (Gomez et al., 2013; Kantelhardt et al., 2015).

Breast cancer subtypes such as estrogen receptor-positive/negative BC, progesterone positive BC, human epidermal growth factor receptor 2 BC and triple-negative BC exist. These subtypes have varying prognoses and can be influenced by genetic, viral, environmental, social and cultural factors (Biancolella et al., 2021; Nwagu et al., 2021). Triple-negative breast cancer subtypes have been reported to be of high incidence in African women and account for 12-20% of all breast cancer (Anders and Carey, 2009).

The African continent is divided into 2 major regions of Sub-Saharan Africa and Northern Africa while Sub-Saharan Africa is divided into 4 sub-regions which comprise: Western, Eastern, Central and Southern Africa. This review aims at bringing together available and accessible research papers on breast cancer statistics and scenarios across the different regions in Africa for better policy enactment and implementation to reduce the breast cancer burden in Africa.

Breast Cancer in West Africa Region

In the African continent, Western Africa has been reported to have the highest cancer burden when incidence and mortality rate were taken into consideration with breast cancer being the leading cause of death in women when compared with cervical cancer (Azubuike et al., 2018). The incidence rate of breast cancer in Western Africa has been reported to be stable since 2002 possibly due to limited changes in the lifestyle of the people that may favour its increase (Hamdi et al., 2021). The fatality rate of breast cancer has been reported to be high in Western Africa when compared with Northern and Southern Africa which is lower (Hamdi et al., 2021). The age-standardized incidence (ASIR) and mortality rates (ASMR) per 100,000 women per year in Western Africa were reported to increase by 17.6 % and 5.5 % respectively, between 2008 (ASIR: 31.8; ASMR: 19.0) and 2012 (ASIR: 38.6; ASMR: 20.1) based on estimated changes from GLOBOCAN 2012 (Ferlay et al., 2008; Ferlay et al., 2015; Azubuike et al., 2018). Also, the high ASMR recorded when compared with other sub-regions in Sub-Saharan Africa (SSA) may be due to the high mortality rate observed in Nigeria. An estimated 5-year survival for breast cancer in West Africa was reported to be 35.2% (Ssentongo et al., 2019). According to GLOBOCAN 2018, ASIR and ASMR were 37.3 and 17.8 per 100000 women, respectively, which is slightly lower than what was reported in GLOBOCAN 2012 (Sharma, 2020). The estimated 5-year survival rate (MIR) of 0.30 according to GLOBOCAN 2018 was higher than that of other African regions (Sharma, 2020).

Nigeria was reported to have the highest incidence rate of 50.5 per 100,000 women in Western Africa when compared with other countries in the sub-region and the second highest in the Sub-Saharan Africa region (Ferlay et al., 2015; Azubuike et al., 2018). It also had the highest age-standardized mortality ratio of 25.9 per 100,000 women in Sub-Saharan Africa (Azubuike et al., 2018). The incidence rate of breast cancer in Nigeria has been reported to have increased since the period of 1960-1969 from 13.7 to 50.4 in the period 2002-2012 with a projected increase of 84.2 between the period 2013-2030 (GLOBOCAN, 2012; Jeddy-Agba et al., 2012; Azubuike et al., 2018). A study of 1342 cases in Ghana showed that most patients were presented at an advanced stage and a mean age of 50.3 years (Edmund et al., 2013).

Furthermore, breast cancer has been reported to occur more in premenopausal women with a mean age of 48 years in Nigeria. Sighko et al. (2013) also observed an increase in the incidence of breast cancer among premenopausal women following the analyses of breast cancer trends in Mali and Gambia between 1987 and 2009. They also reported that late age at menarche was associated with an increased odds ratio for premenopausal breast cancer while it had a protective effect for postmenopausal breast cancer based on a case-control study in Mali. In Ghana, an extended period of lactation had a protective effect on the development of ER-positive and ER-negative breast cancer but this effect is more associated with ER+ breast cancer. Also, the increased parity was reported to be associated with reduced risk of ER+ and ER- breast cancer among women over 50 years but increased early onset of ER tumours (Figueroa et al., 2020).

Tumour biology varies across African countries. Estrogen receptor negative (ER) breast cancer subtype has been reported to be highly prevalent in West African countries when compared with East African countries (Newman and Kaljee, 2017). Also, Hercules et al. (2022) reported that the triple-negative breast cancer subtype (TNBC) had the highest frequency of occurrence (45.7%) when compared with other regions across Africa (14.9%-22.7%). This finding is similar to the observation of an increased prevalence of TNBC/ER-negative breast cancer subtype in the Caribbean and North America due to the majority of their population's West African ancestry. (Zakharia et al., 2009; Moreno-Estrada et al., 2013; Scott et al., 2019). Adjei et al. (2014) reported 76% ER-positive breast cancer among 51 cases following biopsy analysis. A prevalence of 51% for TNBC was reported for Ghana when compared to 16% for East Africa (Jiagge et al., 2016). HER2 breast cancer has been reported to be overexpressed in 18% of breast cancer patients in Mali (Ly et al., 2012). Higher expression of HER2 has also been reported in older Congolese women (Luyeye et al., 2015).

Since genetic mutation can predispose to cancer of any type, hereditary breast cancer is associated with either BRCA1 or BRCA2 gene mutations. A report from Nigeria between 1998 to 2011 involving 1,715 premenopausal women showed that 25% of pregnancy-associated breast cancer (PABC) cases were associated with BRCA1/2 genetic mutation carriers (Hou et al., 2013).

Two separate studies in Ghana and Nigeria have shown that information on breast cancer was mostly obtained from mass media and that there is poor knowledge of breast cancer risk factors (Opoku et al., 2012; Azubuike, 2017). On breast examination in Ghana, it was reported that self-examination and clinical examination were applied more than mammogram screening (Opoku et al., 2012). 

Breast Cancer in East Africa Regio

The East Africa region though characterized by young age presentation, and a lower incidence rate, is associated with age-standardized incidence and mortality rates of 29.9 and 15.4 per 100,000 women, respectively, and estimated five-year survival of 37.7% (Bray et al., 2018; Ssentongo et al., 2019; Sharma, 2020; Popli et al., 2021). Sharma (2020) reported East Africa's MIR to be 0.50 which was slightly lower than that of Central Africa. This implies that the 5-year survival rate for East Africa was slightly better than that of Central Africa. Mortality due to breast cancer has been aggravated by late diagnosis and poor treatment standards (Scheel et al., 2020; Popli et al., 2021).

Just like in other sub-Saharan African (SSA) countries, breast cancer remains the most common cause of cancer-related morbidity and mortality among women in Kenya according to the 2015 Kenya Stepwise Survey of Non-Communicable Disease Risk Factors Report (Korir et al., 2020). Despite the Kenyan government's establishment of the National Cancer Control Strategy, breast cancer screening rates for women remain low at about 5%, making early detection difficult (Kisuya et al., 2014; National Cancer Screening Guidelines, 2018). In Kenya, breast cancer's peak age of occurrence in women is between 50-59 years (Korir et al., 2020). Also, Antabe et al. (2020) reported that breast cancer awareness and screening are taken into cognizance by older women when compared with younger women hence they advocated for increased awareness among young women. Factors noted to influence breast cancer screening in Kenya are educational level, marital status, residential area, financial constraints, religion, lifestyle and ethnic origin (Kiecolt-Glaser and Newton, 2001; Rohrer et al., 2005; Ganle, 2015; Antabe et al., 2020).

In Uganda (Kampala), the average annual percentage change in the incidence rate of breast cancer was estimated at 4.5% between 1991 and 2006 while that of Zimbabwe (Harare) between 1991 and 2010 was 4.9% (Parkin et al., 2010; Chokunonga et al., 2013). The incidence rate of breast cancer has been reported to be highest in the urban areas of Kenya, Mauritius and Seychelles (Joko-Fru et al., 2020). 

Reports on breast cancer sub-type from certain East African countries showed that 47% of 113 patients (Uganda) and 72.8% of 301 patients (Kenya) had estrogen receptor-positive (ER+) breast cancer cases (Galukande et al., 2013; Sayed et al., 2014). A similar report by Popli et al. (2021) based on a meta-analysis across five East African countries (Kenya, Ethiopia, Rwanda, Uganda and Tanzania) showed that ER+ breast cancer (55%) was the predominant subtype while that of human epidermal growth factor receptor-2 (HER2) and triple-negative breast cancer (TNBC) subtypes were 23% and 27%, respectively, across the countries studied. It was also observed that there is widespread suboptimal use of endocrine therapy in the treatment of ER+ breast cancer in the region while that of HER2-positive breast cancer is expensive and not readily available in Sub-Saharan Africa (Gershon et al., 2019; Popli et al., 2021). Limited research data on BRCA status in East Africa was reported, as available data on BRCA mutations are mostly from North Africa and West Africa (Karami and Mehdipour, 2013; Newman, 2015; Popli et al., 2021). in East Africa, most cases of breast cancer were presented at a late stage due to limited breast cancer screening (Popli et al., 2021). 

Based on patient presentation, in Ethiopia, 71% of 1070 women in a cohort study from 2005-2010 were presented with stage 3 of breast cancer and the median age of most women in the cohort was 43 years (Kantelhardt et al., 2014; Kantelhardt et al., 2015). In Rwanda, a study of 145 cases reported the mean age of women who presented for breast cancer to be 48.5 years (Mody et al., 2013) while in Eritrea, the mean age of 82 patients who presented for breast cancer was 48 years with two-thirds being at stage 3-4 (Tesfamariam et al., 2013). A recent metanalysis data of publications from Africa between 2010 and 2019 involving 33,199 breast cancer patients showed that 38% of the patients from East Africa were diagnosed before 40 years (Olayide et al., 2021). A case-control study from Tanzania showed that a high body mass index (BMI) at age 20 increases the odd ratio (OR) of breast cancer in premenopausal and postmenopausal women while long-term lactation and late age at menarche decreased the OR of premenopausal breast cancer (Jordan et al., 2013). 

Breast Cancer in Central Africa Region

The incidence rate of breast cancer in Central Africa was estimated to be 26.8 per 100,000 women (Ferlay et al., 2013). According to Sharma (2020) analysis of the GLOBOCAN 2018 breast cancer report, ASIR and ASMR were 27.9 and 15.8 per 100000 women, respectively, which is slightly higher than what was reported by Ferlay et al. (2013) and a MIR of 0.54 which reflects the lowest 5-year survival rate in the African continent. Also, two countries in this region recorded the lowest 5-year survival rates (as reflected in MIR) of 0.68 and 0.64 for the Central Africa Republic and Equatorial Guinea, respectively, when compared with other Sub-Saharan countries (Sharma, 2020)

Balekouzou et al. (2017) reported a case-control study that covered records of breast cancer cases from September 2003 to September 2015 from Bangui in the Central Africa Republic with a focus on the relationship between socio-demographic factors and breast cancer as well as reproductive factors and breast cancer. The research findings on the reproductive factors and breast cancer, women with abortion history (5.41) and nulliparous women (1.98) had higher odds of breast cancer when compared with women with no abortion and pluriparous women, respectively, while decreased odds of breast cancer were observed in those women with regular menstrual cycles (0.44) and late menarche (≥12 years old) women (0.18) when compared with those with irregular menses and early menarche (<12 years old), respectively (Balekouzou et al., 2017). Furthermore, lower odds of breast cancer were significantly associated with women who practiced long breastfeeding period (0.20) and carried a pregnancy to term (0.26) in the same report by Balekouzou et al. (2017). The major limitations to Balekouzou et al. (2017) findings were the small sample population, information and selection bias.

In Rwanda, a case-control study on premenopausal breast cancer involving 340 participants (170 controls and 170 cases) with an average age of 39 years revealed that 98.2 % of the breast cancer cases were invasive ductal carcinoma and 51.2% were in advanced stages (III and IV). Also, same report shows that 60.6% of the BC subtypes (TNBC enriched 12.9%, HER2 14.7%and unclassified 32.9%) observed were associated with poor prognosis. Again, at various odds ratios, lifestyle risk factors such as alcohol intake, nulliparity, primary infertility history, benign breast disease history, adolescence or early adulthood obesity/overweight were implicated in premenopausal breast cancer occurrence (Ntirenganya et al., 2021).

Breast Cancer in South Africa Region

The incidence and mortality rates of breast cancer in Southern Africa have been estimated to be 38.9 and 15.5 per 100000 women (Ferlay et al., 2013). According to Sharma (2020) analysis of the GLOBOCAN 2018 breast cancer report, ASIR and ASMR were 46.2 and 15.6 per 100000 women, respectively, which is higher than what was reported by Ferlay et al. (2013) and a MIR of 0.34. Advanced-stage cancer incidence was reported to be 50 and 55% in Southern Africa (Cubasch et al., 2013; Langenhoven et al., 2016).

A report by Singh et al. (2017) on breast cancer trends in South Africa from 1994 to 2009 showed that 85,561 females had cancer based on their National Cancer Registry with 79.2 % of the females being black, 8.9% Whites, 8.9% Coloured and 2.5% Asians. Based on same report, the ASIR ranged from 26.9 to 51.2 per 100000 with respect to the different ethnic groups in South Africa in 2009. Meanwhile, the ASIR’s between 1994 and 2009 were comparable 25.1 and 26.9 per 100000. Singh et al. (2017) also reported that the life time ratio (LR) for breast cancer increased from 1:36 (1994) to 1:33 (2009) with the Black and Coloured population having the highest LR increase from 1:81 (1994) to 1:49 (2009) and 1:63 (1994) to 1:22 (2009), respectively. There was also an increase in the proportion of breast cancer among all female cancer types from 17.3 in 1994 to 20.8 in 2009. Furthermore, the MIR was reported to have increased from 0.35 in 1997 to 0.52 in 2007. On screening in South Africa general population, Phaswana-Mafuya and Petlzer (2018) reported that breast cancer screening was low when compared with cervical cancer screening, as represented by the 13.4% mammography screening as opposed to the 52.0% Papanicolaou (PAP) smear test.

For breast cancer subtype, HER2 was reported to be overexpressed in 26% of South African patients (McCormack et al., 2013). Shulman et al. (2016) report from Botswana showed that breast cancer represents 18% of all cancer type and 12.5% of cancer related deaths.

Breast Cancer in North Africa Region

According to Sharma (2020) analysis of the GLOBOCAN 2018 breast cancer report, ASIR and ASMR were 48.9 and 18.4 per 100000 women, respectively which was higher when compared to reports for other African regions, and a MIR of 0.37. Breast cancer was reported to constitute 35.8% of all new cancer diagnosis in Morocco (Khalis et al., 2018). An age-matched case-control study carried out between January 2014 to April 2015 involving 474 women (equal number of cases (237) and controls (237)) shows that early menarche (≤13 years) and nulliparity contributes significantly to the risk of breast cancer while early age at first full term birth (<20 years) decreases risk of breast cancer (Khalis et al., 2018). The mechanism behind nulliparity and increased breast cancer risk has not been fully explored but early menarche and increased breast cancer risk has been associated to prolonged exposure of the epithelium of the breast to estrogen during ovarian activity (Clavel-Chapelon, 2002).

An evaluation of 124 young Tunisian women below 35 years of age revealed that 14 had stage 4 breast cancer with overall 5-year survival of 67.7% (Bouzid et al., 2013). A study in Morocco showed that the incidence of Stage III and IV breast cancer was 33% (Rais et al., 2012). The odds ratio of having breast cancer in Tunisia increases with the late stage of childbirth, early menarche, null parity and family history of breast cancer (Msolly et al., 2013). 

Breast cancer subtypes vary across the African continent. About 17.5% of Sudan and 27% of Egypt cases have an overexpression of HER2 breast cancer subtype (Awadelkarim et al., 2008; Salhia et al., 2011). Among all breast cancer subtypes, TNBC occurred in 23 and 28% of women in Tunisia and Egypt, respectively (Rais et al., 2012; Corbex et al., 2014).

The findings from a case-control study between 2009 and 2015 on the risk factors associated with  inflammatory and non-inflammatory breast cancer in Egypt, Tunisia and Morocco revealed the following: that women with early menarche before 12 years were at higher risk of both inflammatory and non-inflammatory breast cancer; birthing five or more children was associated with higher risk of inflammatory breast cancer (IBC); nulliparous women had a reduced risk of inflammatory breast cancer when compared with those with early first birth before 20 years; the last birthing at an age greater or equal to 35 years was associated with increased inflammatory breast cancer risk; exclusive breastfeeding was associated with increased risk of IBC; problems associated with lactation breast also increases the risk of both cancer types while difficulty in conception was not associated with any of the breast cancer types (Schairer et al., 2020). Increased risk of both IBC and non-IBC was linked to a non-lactation breast problem, breast trauma and family history of breast cancer but diabetes, exposure to farm life, pesticides, fieldwork, soap production and animal care were all associated with increased risk of IBC only (Schairer et al., 2020). Socioeconomic status was also associated with an increased risk of all breast cancer types (Mourali et al., 1980; Awatef et al., 2013; Schairer et al., 2020). Atkinson  et al. (2016) report on reproductive factors associated with inflammatory breast cancer involving 224 cases revealed that women with body mass index ≥25 kg/m2, breast feeding, smoking history and age at first pregnancy (≥26) are modifiable factors that influences the risk of IBC.

Conclusion

Reports from various regions of the African continent showed that more investigations into breast cancer screening, awareness, treatment and subtypes are needed to foster the understanding of various risk factors associated with breast cancer with the aim of reducing the growing breast cancer burden in Africa. 

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