Epidemiology of Breast Cancer in Sub-Saharan Africa

Abstract

Breast cancer has increasingly become a disease of high morbidity and mortality globally, and in the sub-Saharan African region in particular. Therefore, there is a need to review the current status of breast cancer in the region in the last decade. Though Africa has one of the lowest incidence rates, it has the highest mortality rate globally. There have been reported inter- and intra-country variations in breast cancer morbidity and mortality in the region, with East Africa having the largest incidence rate increase, while southern Africa experiences the lowest increase between 2008 and 2012. Histology remains the commonest modality of diagnosis in sub-Saharan Africa; with invasive ductal cancers being the commonest among patients. Novel genes have also been popular among certain populations, in the presence of the more popular BRACA genes. Adverse outcomes reported include physical and mental health outcomes, which have been linked to some health behaviours. There has been varying modalities of treatments across the region. Therefore, there is a need for better organized and improved screening/diagnostics service accessibility in resource-constrained settings in sub-Saharan Africa. There should also be increased awareness creation among African populations about the availability of treatment facilities and modalities in their communities.

1. Introduction

Breast cancer is the most common cancer among women and one of the most important causes of death among them. Breast cancer (BC) is the most frequently diagnosed cancer in women worldwide with 2.3 million new cases in 2020 and the fifth leading cause of cancer mortality, with 685,000 deaths [1, 2]. It ranks first for incidence in the vast majority of countries (159 of 185 countries) and mortality in 110 countries, and it accounts for 11.7% of all incident cancer cases – just ahead of new lung cancer cases [2]. It is the leading cause of cancer-related morbidity and mortality among women; accounting for 24.5% of all incident cancer cases and 15.5% of cancer-related mortality [2]. Incidence rates are 88% higher in transitioned countries than in transitioning countries (55.9 and 29.7 per 100,000, respectively), with the highest incidence rates (>80 per 100,000) in Australia/New Zealand, Western Europe (Belgium has the world’s highest incidence), Northern America, and Northern Europe and the lowest rates (<40 per 100,000) in Central America, Eastern and Middle Africa, and South-Central Asia [1, 2]. High and very high HDI countries have 55.9 incidence ASR per 100,000 females compared to 29.7 incidence ASR per 100,000 females globally [2]. Furthermore, China has the highest proportion of incident cases of breast cancer, globally; accounting for 49.3%, 49.9%, and 48.6% of total incidence rates overall, males and females, respectively [2]. The burden of breast cancer has been projected to reach over 3 million incident cases and 1 million deaths every year by the year 2040 [1].

Generally, the global burden of breast cancer is reported to be an age-standardized incidence rate of 43.3 per 100,000 women per year and an age-standardized mortality rate of 12.9 per 100,000 women per year. The more developed countries significantly have a higher incidence rate (74.1 per 100, 000 women per year) and mortality rate (14.9 per 100,000 women per year) compared to the less developed countries with an incidence rate of 31.3 per 100,000 women per year and mortality rate of 11.5 per 100,000 women per year [3]. High and very high HDI countries have a 12.8 mortality ASR per 100,000 females compared to a 15.0 mortality ASR per 100,000 females globally [2]. While Western Europe has the highest incidence of breast cancer (90.7 incidence ASR per 100,000 women); the West African region and Melanesia have the highest mortality (22.3 and 27.5 ASR per 100,000 women, respectively) [2]. Furthermore, China has the highest proportion of breast cancer-related mortality rates, globally; accounting for 58.3%, 60.6%, and 55.5% of total mortality rates overall, males and females, respectively [2].

Incidence rates of breast cancer are rising fast in transitioning countries in South America, Africa, and Asia as well as in high-income Asian countries where rates are historically low [2]. Dramatic changes in lifestyle, sociocultural, and built environments brought about by growing economies and an increase in the proportion of women in the industrial workforce have had an impact on the prevalence of breast cancer risk factors—the postponement of childbearing and having fewer children, greater levels of excess body weight and physical inactivity—and have resulted in a convergence toward the risk factor profile of western countries and narrowing international gaps in breast cancer morbidity [4].

Incidence and death rates have increased over the last three decades due to longstanding higher reproductive and hormonal risk factor profiles (such as early age at menarche, later age, at menopause, advanced age at first birth, fewer number of children, less breastfeeding, menopausal hormone therapy, oral contraceptives, diethylstilbestrol), behavioral risk factors (alcohol intake, smoking, excess body weight, physical inactivity, insufficient vitamin supplementation, intake of processed food, excessive exposure to artificial light, exposure to chemicals and other drugs), higher prevalence of breast cancer-associated genes, better cancer registration, and cancer detection [4, 5, 6, 7]. The non-modifiable factors include female sex, older age, family history, ethnicity/race, genetic mutation, pregnancy and breastfeeding, menstrual period and menopause, the density of breast tissue, previous history of breast cancer, noncancerous breast diseases and previous radiation therapy [7]. The incidence rate of breast cancer varies greatly with race and ethnicity and is higher in developed countries [2, 4, 6].

Literature has shown that the mortality rate of breast cancer is higher in less developed regions [2, 6]. women living in transitioning countries have 17% higher mortality rates compared with women in transitioned countries (15.0 and 12.8 per 100,000, respectively) because of high fatality rates, with the highest mortality rates found in Melanesia, Western Africa, Micronesia/Polynesia, and the Caribbean (Barbados has the world’s highest mortality) [2]. A 5 -year survival variation analysis for breast cancer has now been said to be close to 90% in the US and Australia; while as low as 40% in South Africa according to a CONCORD-3 study of cancer survival in 71 countries [8].

There is thus a need to review the epidemiology of breast cancer in the last decade; examine gaps and proffer recommendations to aid the prevention and control of breast cancer in sub-Saharan Africa.

1.1 The burden of breast cancer in sub-Saharan Africa

Breast cancer is the leading diagnosed cancer and the second most common cause of cancer mortality in sub-Saharan Africa. Sub-Saharan Africa has the highest age-standardized incidence rate of 17.3 per 100,000 women per year, globally; with the Southern Africa region and West African region having the highest age-standardized incidence rate of 38.9 and 38.6 per 100,000 women per year in sub-Saharan Africa, respectively. However, the Northern Africa region has the highest incidence rate of 43.2 ASR incidence in the whole of Africa [3]. Country-specific prevalence shows that there is a 15.3%, 4.6% and 3.3% prevalence of breast cancer in the Central African Republic, Rwanda and Sierra Leone, respectively [9, 10]. Mauritius and Nigeria have been said to be the countries with the highest incidence in Africa at 64.2 and 50.4 ASR incidence per 100,000 repetitively [3].

The 5-year age-standardized relative survival in 12 sub-Saharan African countries was 66% for cases diagnosed during 2008 through 2015, sharply contrasting with 85% to 90% for cases diagnosed in high-income countries from 2010 through 2014 [8]. A multi-country estimate of 3-year survival of breast cancer patients was 50% [95%CI: 48, 53] between 2014 and 2017 [11]. Western African region has the highest mortality rate of 20.1 ASR mortality per 100,000; with central African region having the least mortality rate of 14.9 ASR mortality globally. However, Nigeria has the highest mortality rate in Africa with 25.9 ASR mortality per 100,000 [3]. This is, nonetheless, higher than the world average of 12.9 ASR mortality [3].

Population-specific variations in 3-year mortality rates have also been reported across sub-Saharan Africa; with a survival range of 90% among white women to 56% in black Namibian women; and in South Africa where survival ranges from 76% among mixed-race women to 59% in black women [11]. Country-specific variation in 3-year mortality shows a 44–47% survival rate in Uganda and Zambia compared to the 36% survival rate in Nigeria [11].

The population-specific 5-year survival ASR was as low as 5% [95%CI: 1.9, 11.3] in Uganda (Kyadondo) and as high as 80% [95%CI: 22.2, 96.8] and 93.7% [95%CI: 75.5, 98.5] in Namibia and Mauritius, respectively [12]; comparable to 55% in the US state of Connecticut and 57% in Norway during the late 1940s, 48 3 decades before the introduction of mammography screening and modern therapies [2]. Survival also varies within countries in sub-Saharan Africa. For example, in Zimbabwe 3-year relative survival rate in the capital (Harare) is 56.7% [95%CI: 48.2, 64.6] compared to 21.6% [95%CI: 8.2, 39.8] reported in Bulawayo [12].

These variations can be said to be due to the level of access to early diagnosis and prompt treatment of breast cancer cases across the continent; with up to 22% survival increase in Nigeria, Uganda and Zambia [11]. Further explanation for the variations between countries may also be a result of their level of human development index (HDI). For example, though Mauritius (a country with a very high HDI) has the highest incidence rate of breast cancer in Africa [3]; it also has the highest survival rate compared to Zimbabwe (medium HDI) with a lower survival rate [12]. This shows that though, Mauritius detects more breast cancer patients; most of whom were able to survive beyond the 5-year survival period – which can be due to improved access to prompt diagnosis and early treatment for a better outcome.

Because organized, population-based mammography screening programs may not be cost-effective or feasible in low-resource settings [13], efforts to promote early detection through improved breast cancer awareness and clinical breast examination by skilled health providers [14], followed by timely and appropriate treatment, are essential components to improving survival. A recent study conducted in 5 sub-Saharan African countries estimated that 28% to 37% of breast cancer deaths in these countries could be prevented through an early diagnosis of symptomatic disease and adequate treatment, with a fairly equal contribution of each [11]. The Breast Health Global Initiative has established a series of evidence-based, resource-stratified guidelines that support phased implementation into real-world practice [15].

2. The distribution of breast cancer in sub-Saharan Africa

Globally, while Africa has one of the lowest age-standardized breast cancer incidence rates (36.2 per 100,000 women per year) after Asia (29.1 per 100,000 women per year); it has the highest mortality rate of 17.3 per 100, 000 compared to other regions of the world. However, the mortality rate is highest (20.1 per 100,000 women per year) in the West African sub-region [3]. Majority of breast cancer patients in sub-Saharan Africa are women [16, 17, 18]. A recent systematic review reported that 97% [95%CI: 97–98] of all breast cancer cases in Africa are seen in Females [16]. About 18% prevalence has been reported among male Ethiopians; which is likely the highest in the region among breast cancer patients [16]. Oftentimes, many of these breast cancer rates are obtained from institutional-based records or registries across sub-Saharan Africa; with varying reports across the sub-continent.

More than half (58%) of breast cancer patients were diagnosed before the age of 50 [16]. The median and peak ages have also been reported in some studies. The peak age of incidence of 47.8%, 52.5%, 57.4%, 57.5% and 57.9% between the 3rd and 5^th decades among patients in Rwanda, Lagos-Nigeria, Southern Ethiopia, Central African Republic and Northwest Amhara regions of Ethiopia, respectively [9, 17, 19, 20, 21]. Similar report was observed among breast cancer patients in Adis Ababa Ethiopia with 63.1% at the same peak range [22]. Almost two-thirds of breast cancer patients are below 50 years old in Burkina Faso [23]. Gabretsadik A et al, in a seven-year (2013–2019) review, reported a median age of 38 years among patients in Southern Ethiopia [21]. Ouedraogo SY et al, Balekouzou et al. and Sayed et al. reported a mean age of 45.79 years, 45.85 years, 47.5 years and 47.8% among patients with breast cancer in Burkina Faso, Central African Republic, Kenya and Rwanda [9, 18, 19, 23]. Fatiregun reported a mean age of 49.6 (±11.2) years among breast cancer patients in Lagos, Nigeria [20]. However, a population-based study revealed a much lower average age of 33.4 (± 1.25) in Burkina Faso [24]. This shows that institutional-based studies might present a higher age level compared to the population-based study and give an illusion of higher average age of patties with breast cancer. Thus, studies must indicate the study setting to contextualize the study findings.

It was also observed that the number of cases diagnosed or reported is dependent on the distance of communities from the health facilities offering screening, diagnosis and treatment. For example, Gabretsadik et al. reported a higher number of cases in zones and districts closest to the tertiary hospital in Hawassa city; with the number of cases observed to thin out as the distance increases away from this specialist University hospital. It can be said that, unless a population-based survey is done, the true incidence/prevalence and distribution of breast cancer in communities in sub-Saharan Africa may be unknown and estimates from institutions will be affected by Berksonian Bias [21].

2.1 African trends on breast cancer

Some of the most rapid increases are occurring in sub-Saharan Africa. Between the mid-1990s and the mid-2010s, incidence rates increased by >5% per year in Malawi (Blantyre), Nigeria (Ibadan), and Seychelles and by 3% to 4% per year in South Africa (Eastern Cape and Zimbabwe (Harare) [25]. Between 2008 and 2012, East Africa experienced the largest incidence rate increase of 36.5% from 19.30 ASR in 2008 incidence to 30.4 ASR in 2012. However, the incidence remains highest in the North African region at 43.2 ASR; with southern Africa having the lowest increase of 2% from 38.2 ASR incidence in 2008 to 38.9 ASR incidence in 2012 [3]. In southern Ethiopia, there has been an increasing incidence of breast cancer between 2013 and 2019 according to institutional records. It has increased from 12.3% in 2013 to 19.0% in 2019 [21]. Nigeria has continuously shown increases in incident rates from 13.7 ASR between 1960 and 1969 to 50.4 ASR between 2000 and 2012 and has been projected to 84.2 ASR between 2013 and 2050 [3]. In Central African Republic, the average prevalence rate has been on the increase; with breast cancer prevalence just above 10% in 2003 and just above 15% in 2015 among breast cancer patients; after dropping from 20% in 2014 [9].

Mortality rates in sub-Saharan African regions have increased simultaneously and rank now the world's highest, reflecting weak health infrastructure and subsequently poor survival outcomes. Between the same periods, East Africa also showed the largest increase of 26% mortality from 11.4 ASR in 2008 to 15.6 ASR in 2012. Southern Africa has the least mortality rate reduction of 24.5%; with a reduction from 19.3 ASR mortality in 2008 to 15.5 ASR mortality in 2012 [3]. This has been said to be due to the human development index of the country and stage at diagnosis. For example, low HDI (HR: 2.3 [95%CI: 1.4, 3.7]; p = 0.001) and medium HDI (HR: 1.9 [95%CI: 1.2, 3.1]; p = 0.01) countries are more likely to have higher odds of breast cancer-related mortality compared to African HDI countries. Patients in late stages at presentation have higher odds (HR: 2.5 [95%CI: 1.8, 3.3]; p < 0.001) of breast cancer-related deaths compared to those who presented at the early stage of the disease [12].

2.2 Determinants/risk factors of breast cancer reported in the last decade

Various factors have been associated with the development of breast malignancies across sub-Saharan Africa in the last decade. Body size has been associated with the development of breast cancer. A recent study from Ghana, by Brighton LA et al, reported that increasing body size increased the likelihood of breast cancer (slightly heavy body size – OR: 1.30 [95%CI: 1.04, 1.62] and heavy body size – OR: 1.50 [95%CI: 1.11, 2.02]) among patients with suspicious lesions of breast cancer [5]. Level of education has also been associated with the development of breast cancer among Populations in the region. The higher the level of education, the higher the likelihood of the development of breast cancer. Also from the same Ghanaian study, those with at least secondary school education (more than basic education) are significantly more likely to develop breast cancer compared to those without formal education. (OR:1.50 [95%CI: 1.21, 1.87]; p < 0.01) [5]. The number of births has also been said to reduce the likelihood of breast cancer. multiparous women (at least 5 orders) are significantly less likely to develop breast cancer compared to nulliparous Ghanaian patients (parity ≥5 - OR: 0.71 [95%CI: 0.52,0.97]; p < 0.01) [5].

3. Types of breast cancer

These are often obtained from clinical, histopathological and genomic diagnoses. Availability and accessibility of these are, however, varying in sub-Saharan Africa. This had affected presentation, reportage, early screening and diagnosis and treatment of breast cancer in the region. In many countries, breast cancer is still commonly confirmed by histology (85%); and 6% cytological confirmed; while 9% were clinically confirmed in many sub-Saharan African countries [11]. Fine needle aspiration (FNAC) and biopsy remain the commonly reported means of diagnosis; as it stands at 60% and 37.9%, respectively in Ethiopia [21].

About half (52.5%) of all suspicious breast lesions have been reported to be malignant; with 36% being benign conditions in some African populations [5]. Invasive ductal cancers appear to be the commonest among African populations accounting for more than half of all reported breast cancers [9, 17, 18, 19, 21]. This is congruent with globally reported histological type reported globally; which has been reported to be 40–80% [7]. It ranges between 55.3% in Southern Ethiopia and 84.2% in Kenya [18, 21]. Tumor behavior reported includes moderately differentiated in 31.7% of cases and poorly differentiated in 27.7% of cases in Southern Ethiopia. Only 13.6% were reported to be well-differentiated among Ethiopian patients [21].

Molecularly, BRACA 1 and BRAC 2 remains the commonest molecular gene for breast cancer in African populations. Each accounts for 5.6%, respectively, in sub-Saharan Africa the populations. Other reported genes include ATM (1.5%), PALB2 (1%), BARD1 (0.5%), CDHI (0.5%) and TP53 (0.5%) [26]. This is in line with the global commonly reported genes of 45–87% of BRACA 1, and 50–85% for BRACA 2 [7]. Novel variants of these genes have been reported to predominate in certain sub-Saharan African regions. This includes the PIK3CA genes and the TP53 genes; which account for 39.09% and 12.78%, respectively in Burkina Faso [23].

Most cases of breast cancer in the last decade have presented with unilaterally located left breast cancer across sub-Saharan Africa [9, 16, 19, 21, 27]. The highest prevalence of bilateral breast cancer was reported at 8% [95%CI: 6, 12] in Nigeria [16]. Country-specific prevalence of left breast cancer has been reported across the sub-region. For example, Gabretsadik A et al. and Kramer and Colleagues; Ouedrago SY et al. and Uyisenga JP et al. reported that 54%, 52.2%, 51% and 50% of most breast cancer cases are on the left breast among Southern Ethiopian, Rwanda, South African patients and Burkinabe patients [19, 21, 23, 27]. Balekouzou A et al. reported that the left breast is more commonly affected compared the right (12% versus 4%, respectively) among patients in Central African Republic [9].

4. Common breast cancer outcomes

Krammer et al. reported that 75% of patients reported the presence of any pain or disability while only 9% experienced severe pain and disability among South African patients [27]. It was further reported that the presence of the tumor on the right side (OR: 0.31 [95%CI: 0.10, 1.03];p < 0.05); being a Caucasian (OR: 0.21 [95%CI: 0.05, 0.82]; p < 0.05); not being on chemotherapy (OR: 0.39 [95%CI: 0.18, 0.83]; p < 0.05); had axillary lymph node dissection (OR: 0.48 [0.23, 0.98]; p < 0.05) and older age (OR: 0.93 [95%CI: 0.93, 0.98];p < 0.01) are significantly less likely to report cancer-related pains compared to others of differing corresponding attributes [27]. Also, reported is that those not on chemotherapy are significantly less likely to experience disabilities compared to those treated with chemotherapy (OR: 0.37 [95%CI: 0.18, 0.77]; p < 0.01) [27].

It was also reported that 36.6% of South Africans with breast cancer in the Western Cape have depression [28]. However, a lower prevalence of depression (25%) was reported similar population in Addis Ababa, Ethiopia [22]. This has been said to be due to body change stress; in which a higher body change stress significantly predicts depression (β = 0.38; p = 00) among breast cancer patients [28]. It has also been said to be due to perceived social support; in which a lower perceived social significantly predicts depression (β = −0.30; p = 0.01) among breast cancer patients [28].

Also reported is 34.3% psychological distress among South African patients with breast cancer [28]. This has been said to be due to body change stress; with a higher body change stress significantly associated with higher psychological distress (β = 0.37; p = 0.00) [28]. It has also been said to be due to perceived social support; with lower perceived social support significantly associated with higher psychological distress (β = −0.27; p = 0.02) among breast cancer patients [28].

Anxiety disorders were also reported as outcomes of breast cancer among patients in sub-Saharan Africa in the sources reviewed over the last decade. For example, Fatiregun OO et al. reported that 19% of breast cancer patients have anxiety disorders; with mixed anxiety and depressive disorder accounting for 44.7%. Predictors for anxiety disorder among this population include the absence of a history of breast cancer (OR: 3.5 [95%CI: 1.2, 7.0];p = 0.006) and early stage of breast cancer (OR: 1.56 [95%CI: 1.12, 2.17]; p = 0.009) [20].

Almost three-quarters (71.03%) of patients with breast cancer have drug-related problems among patients with breast cancer in Gondar, Ethiopia: with 48.6% reporting adverse drug reactions, with 45.8% need for additional drug therapy and 32.7% non-adherence [17]. Comorbidity and the non-use of neoadjuvant chemotherapy have been associated with the development of drug problems among breast cancer patients. Degu A and Kebede K reported that those with comorbidity are three times more likely to develop drug-related problems compared to those who do not have comorbidities among breast cancer patients in Gondar, Ethiopia [17]. Those on neoadjuvant are significantly less likely to have drug-related problems compared to those on other regimens [17].

5. Preventive behaviors and factors associated

5.1 Late and delayed presentation

Most patients often present at a late stage during the course of the disease; with two-thirds (67%) of all African patients presenting at the advanced stage of breast cancer; albeit, 50% seen at stage 3 and 17% seen at stage 4. The highest level of advanced or late presentation is in West Africa; which stands at 67% [16]. A close estimate of a multi-country study of 8 sub-Saharan countries reported an overall late-stage presentation of 64.8%; with the highest (91.7%) among the countries studied being reported in Harare-Zimbabwe and the lowest (42.6%) reported in Seychelles [12]. Similar report has been reported from cancer registries across Africa; and 18% of which are already metastatic at the time of diagnosis. (Joko-Fu WY et al, 2020) Other estimates have reported that 77% of all staged cases were stage III/IV at diagnosis [29]. In Southern Ethiopia, 66.5% of all diagnoses were made at advanced stages (3 and 4) of the disease [21]. Among patients with breast cancer in Rwanda, the diagnosis was made in about half (52.9%) at stage 3 [19]. In Kenya, almost two-thirds (61.6%) of breast cancer patients have stages 3 and 4 when the diagnosis was made [18]. In Lagos-Nigeria and Addis Ababa-Ethiopia, about half (54% and 51.9%, respectively) of the diagnosis was made at stages 3 and 4 among similar patients [20, 22]. However, half (51.7%) of patients have their diagnosis made at stage 2 in Western Cape, South Africa [28]. In contrast, only 19.48% of breast cancer cases were diagnosed at stage 3 among patients in Cape Town, South Africa [27].

The delayed presentation was also reported in the reviewed literature. Only 25% presented within the first 3 months, and 30% within 1 year, of the onset of symptoms among breast cancer patients in Khartoum-Sudan [30]. In the Central African Republic, only 30% presented within the first year of the onset of symptoms among breast cancer patients in Khartoum-Sudan [9]. Also, in Sierra Leone and Rwanda, 66.7% and 88.6% respectively, presented after 12 months among participants in population-based surveys [10].

Many factors have been said to be responsible for delayed or late presentation for screening and treatment for breast cancer among sub-Saharan African populations. A prior diagnosis of breast cancer has been shown to increase the odds of delayed presentation; with those diagnosed within at least 3 months with higher odds of late presentation compared to those diagnosed more recently (3–12 months – OR: 9.6 [95%CI: 9.55, 9.75]; p < 0.00 and >12 months –OR: 9.3 [95%CI: 9.33, 9.33]; p < 0.00) among breast cancer patients in Khartoum, Sudan. The fear of mastectomy/chemotherapy is the commonest reason for delays among Sudanese breast cancer patients [30].

5.2 Non-presentation and use of traditional healers

About 43% and 26.7% of Burkinabe women either do nothing or visit traditional healers, respectively, about their breast-related conditions. Medical advice is only sought in 30% of the cases [24].

5.3 Low utilization of screening services

Early diagnosis has been said to improve survival; with a 3-year relative survival of 78% (95%CI: 71.6–83.3) among those diagnosed at the early stages of cancer compared with 40.3% (95%CI: 34.9–45.7) relative survival when the diagnosis is made at advanced (III and IV) stages of the disease [12]. However, the use of mammography and other screening modalities is very low in sub-Saharan Africa for screening and aiding the diagnosis of breast cancer. This hovers between 3.61% of community-based Ghanaian women and a quarter (23.7%) screening level among community-based women of reproductive age in Namibia.³¹³² Other levels of utilization between these two ends include 5.2% breast cancer screening in the Ivory coast [31]; with 13.4% mammography screening among the south African general women population [32]; mammography screening of 15.5% among older women in South Africa [33]; and 18.6% mammography screening rate among patients in Southern Ethiopia [21].

Several factors have been found to explain the limited use of mammography services. This includes ethnicity, age, level of education, marital status, residence, type of employer, country of residence, wealth index, number of living children, possession of household items of worth, health insurance coverage, level of physical activity and presence of chronic diseases and regular visitation of health facility [31].

Older age is a strong predictor of mammography screening among African women. Phaswana-Mafuya N and Peltzer K reported that older middle-aged (40–49 years) and elderly (60–69 years) significantly increases the likelihood of mammography screening compared to the early middle ages (30–39 years) among South African women; and likelihood increases with age among this population (40–49 years – OR: 2.39 [95%CI: 1.54, 3.69] and 60–69 years – OR: 2.70 [95%CI: 2.70, 8.10]; p < 0.001) [32]. Also, Older women of the reproductive age group (25–49 years) are significantly more likely to access breast cancer screening compared to younger women of the reproductive age group (35–49 years – OR: 1.73 [95%CI: 1.56, 1.91]; p < 0.001; 25–34 years – OR: 1.41 [95%CI: 1.29, 1.54]; p < 0.001) [31]. However, Calys-Tagoe BNL et al. reported that older age is a negative predictor of mammography use. Those that are at least 70 years are significantly less likely to have used mammography screening services compared to younger women in Ghana (≥ 70 years – OR: 0.42 [95%CI: 0.19, 0.93]; p < 0.05) [34].

Also, Ethic group has been said to be an important index of access to mammography services. Calys-Tagoe BNL et al. reported that those of the majority ethnic group are significantly more likely to use mammography services compared to other ethnic groups among Ghanaian women (Akan – OR: 3.41 [95%CI: 1.88, 6.16]; p < 0.001) [34]. This was corroborated by Phaswana-Mafuya N and Peltzer K reported that whites, colored and Asian south Africans were significantly more likely to have mammography services compared to black South African women; with whites having the highest odds of mammography access (whites – OR: 5.06 [95%CI: 3.36, 7.60]; colored – OR: 2.87 [95%CI: 1.87, 4.41] and Indian/Asian 2.52 [95%CI: 1.47, 4.32]) [32]. Further insight was provided by Pelztzer K and Phaswana-Mafuya N as they reported that older adult white ad Indian/Asian adult women are significantly more likely to have used mammography compared to older adult Black South African women. (Asian/Indian – OR: 4.08 [95%CI: 1.71, 9.71]; p < 0.01; whites - OR: 3.33 [95%CI: 1.54,7.19]; p < 0.01) [33]. In this wise, Asian/Indians have higher odds compared to whites which might have been due to the variation in the availability of social support as this demography of south Africans with the highest access to mammography services aged.

An increasing level of education has been said to increase the odds of mammography screening among Sub-Saharan African populations. Phaswana-Mafuya N and Peltzer K reported that south African women with at least grade 8 were reported to be significantly more likely to access mammography services compared to grades 0–7 (grade 8 – OR: 2.25 [95%CI: 1.34, 3.78; p < 0.01; grade ≥ 12 – OR: 2.72 [95%CI: 1.55, 4.77]; p < 0.001) [32]. In fact, Pelztzer K and Phaswana-Mafuya N reported that any level of access to education is a strong predictor of mammography use among older adult south African women compared to those with no formal education. (primary education – OR: 2.76 [95%CI: 2.31, 5.85]; p < 0.01; at least secondary education – OR: 3.81 [95%CI: 1.88, 7.74]; p < 0.001) [33]. Sub-Saharan Africans with at least a formal education are significantly more likely to do breast cancer screening compared to those with no formal education, and the odds of breast cancer screening increase with the level of education. (Primary – OR: 1.77 [ 95%CI: 1.56, 2.01]; p < 0.01; at least secondary – OR: 2.33 [95%CI: 2.05,2.66]; p < 0.001) [31].

Ever being in a partnered relationship is a significant predictor of breast cancer screening among African populations compared to single African populations (married/living with partner – OR: 1.13 [95%CI: 1.04, 1.22]; p = 0.003; widow/divorce/separated – OR: 1.15 [95%CI: 1.03, 1.28]; p = 0.01) [31].

Country of residence is a significant determinant of mammography services use among African populations. Namibians, Burkinabe and Kenyans are significantly more likely to use mammography services compared to Ivoirians; with Namibians having the highest odds of breast cancer screening among the studied African countries (Namibia – OR: 3.3 [95%CI: 2.90, 3.83]; p < 0.001; Burkina Faso – OR: 1.58 [95%CI: 1.32, 1.89]; p < 0.001; Kenya – OR: 1.92 [95%CI: 1.67, 2.21]; p < 0.001) [31].

Place of residence has been shown to determine the use of mammography services among African populations. Phaswana-Mafuya N and Peltzer K reported that rural informal residents are significantly less likely to have used mammography services compared to urban formal dwelling South African women. (Rural informal – OR: 0.40 [95%CI: 0.24, 0.72]; p < 0.01) [32].

Employment status is also a significant predictor of mammography utilization. Ghanaian women who are self-employed and those in the informal sectors are less likely to use mammography services compared to others in the civil service (self-employed – OR: 0.21 [95%CI: 0.11, 0.42]; p < 0.000; informal - OR: 0.26 [95%CI: 0.12, 0.57]; p < 0.001) [34].

Possession of household items of worth has also been said to determine breast cancer screening. Possession of television was reported to increase the likelihood of breast cancer screening among African populations compared to those who do not (possession of TV – OR: 1.17 [95%CI: 1.08, 1.27]; p < 0.001) [31].

Socioeconomic status has been said to be a significant predictor of mammography services utilization. Pelztzer K and Phaswana-Mafuya N reported that south African older adult women with a high wealth index are twice more likely to use mammography services compared to those with a low wealth index (high wealth index – OR: 2.18 [ 95%CI: 1.00, 4.76]; p < 0.05) [33].

Lifestyle behaviors have also been an important determinant of the use of mammography services. Phaswana-Mafuya N and Peltzer K reported that south African women who reported moderate-vigorous physical activity significantly have higher odds of mammography services utilization compared to the physically inactive south African women (moderate-vigorous physical activity – OR: 1.55 [95%CI: 1.12; 2.13]; p < 0.01) [32].

The presence of chronic diseases has also been said to be a strong predictor of mammography service use. South African women with chronic diseases are significantly more likely to use mammography services compared to those with none (at least one chronic disease – OR: 1.49 [95%CI: 1.08, 2.05]; p < 0.05) [32]. Similar outcomes were reported among older South African women by the same authors (at least 2 chronic conditions – OR: 1.92 [95%CI: 1.01, 3.63]) [33].

Access to medical aid has also been said to be a strong predictor of mammography services use. South African women with medical aid were twice significantly more likely to use mammography services compared to south African women who have no medical aid [32]. This was further corroborated by the same authors among Older south African women; where older south African women with health insurance are twice significantly more likely to use mammography services compared to those who are not covered by health insurance (health insurance – OR: 2.71 [95%CI: 1.57, 4.66]; p < 0.001) [33].

Health facility visitation has also been said to be associated with breast cancer screening among women of reproductive age group; with those who frequently visited health facilities reporting higher odds of mammography services use compared with those who do not (OR: 1.37 [95%CI: 1.28, 1.45]; p < 0.001) [31].

6. Common modalities of treatment

Traditionally, breast cancer is commonly treated through chemotherapy, immunotherapy, hormonal therapy, biological therapy, radiotherapy and surgery [7]. Reported modalities of treatment in the last decade reported that chemotherapy, hormonal therapy and surgery remain the mainstay of management in many settings in sub-Saharan Africa in the last decade. Overall, breast cancer patients had surgery; with an overall mastectomy prevalence of 71% [95%CI: 51, 88]; with beast conserving surgery at 1% [95%CI: 0–2]. Chemotherapy was used in the treatment of 83% [95%CI: 64, 96]; and 77% received hormonal therapy for their treatments in the region [16]. However, country-specific treatment modalities have been reported at varying rates and types across sub-Saharan Africa.

Gabretsadik reported the use of chemotherapy, surgery and hormonal therapy in southern Ethiopia; where Doxorubicin, cyclophosphamide and paclitaxel every 3 weeks for 8 cycles are used for the treatment of stage 1–3) was reported in 59% of cases; doxorubicin and cyclophosphamide every 3 weeks for 6 cycles was reported in 41% of cases and modified radical mastectomy was reported in 35.1% of cases [21]. Also, hormonal therapy has been reported for premenopausal men and women; in which Tamoxifen use was reported in 76.7% of cases. For hormonal therapy for post-menopausal women in which anastrozole after surgery has been reported in 23.3% of cases. Chemotherapy alone, chemotherapy plus surgery and chemotherapy, surgery and hormonal therapy are reported in 65%, 20% and 35%, respectively [21].

Degu A and Kebede K reported different regimens used in the management of breast cancer patients in Gondar, Ethiopia. The commonest regimen was an Adriamycin-Cyclophosphamide combination (Adjuvant and Neoadjuvant, 43% and 22% respectively) and Tamoxifen (Adjuvant and Neoadjuvant, 30% and 8%, respectively) [17].

Kramer and colleagues reported the use of modified radical mastectomy surgery among 73.35% of patients; Axillary lymph node dissection in 78.23%; chemotherapy in 72.78%; hormonal therapy in 70.49% of cases and radiotherapy in 63.32% of cases. Similarly, different combinations of these modalities of treatment were also reported: wide local excision and radiotherapy in 95.24%; modified radical mastectomy and chemotherapy in 88.44% of cases; wide local excision and chemotherapy in 78.85% of cases and modified radical mastectomy and radiotherapy in 57.65% of cases among south African patients [27]. Similarly higher utilization rates of different modalities have been reported from the Central African Republic; where it was reported that 95.4% had surgery; and 91.4% having had chemotherapy and a lower 30.4% having had radiotherapy in the course of breast cancer treatments among patients [9].

Almost similar modalities of treatment were reported among Patients in Burkina Faso where 72.9% and 74.4% had chemotherapy and surgery, respectively. However, a lower proportion (28.6%) of these patients had radiotherapy [23]. Similar reports were observed in Addis Ababa-Ethiopia, where 83.9% had chemotherapy, and 88.1% had had surgery; with 7.9% and 11.4%, having had radiotherapy and hormonal therapy, respectively [22]. Lower utilization has however been reported in Lagos-Nigeria where 50% had chemotherapy; 28.5% have had a combination of chemotherapy and surgery; with 12.5% have had chemotherapy and radiotherapy, and 9.0% had radiotherapy only [20].

7. Strategies to prevent the growing burden of NCDs in sub-Saharan Africa

Establishing primary prevention programs for breast cancer remains a challenge. Nevertheless, efforts to decrease excess body weight and alcohol consumption and to encourage physical activity and breastfeeding may have an impact on stemming the incidence of breast cancer worldwide. Population-wide breast cancer screening programs aim to reduce breast cancer mortality through early detection and effective treatment [2]. Reports have indicated that women who participated in breast cancer screening programs have a lower risk of dying from breast cancer compared with the corresponding risk from nonparticipants [2, 35].

There should be early diagnosis and prompt treatment to prevent and control breast cancer globally, specifically in sub-Saharan Africa. The WHO recommends organized, population-based mammography screening every 2 years for women at average risk for breast cancer aged 50 to 69 years in well-resourced settings [13]. The American cancer society (ACS) recommends that generally, women should have the opportunity to begin yearly screening for women between 40 and 44 years. This should continue as long as they are in good health and have a life expectancy of at least 10 years. ACS strongly recommends that women with an average risk of breast cancer should begin mammography screening beginning at age 45. Those between 45 and 54 years should be screened annually and those at least 55 years should be screened biennially or whenever an opportunity comes up [36]. Clinical breast examination is not directly effective in reducing breast cancer mortality among average-risk women at any age according to guidelines and recent systematic reviews [14, 36].

Mammographic screening, however, has limitations, such as overdiagnosis and overtreatment [2, 37, 38]. There are opportunities to improve the cost-effectiveness and benefit-to-harm ratio of screening by adopting a risk-stratified screening strategy using existing and evolving risk prediction models [2, 37]. Therefore offering breast cancer only to women with higher risk can improve the cost-effectiveness of screening, maintains the benefits and reduce overdiagnosis [37]. Ongoing screening trials are evaluating the clinical acceptability, cost and utility of risk-stratified screening programs in the general population [2, 39, 40].

The establishment and funding of cancer registries is a veritable tool in the prevention and control of breast cancer in sub-Saharan Africa as it can generate recent, accurate data on the incidence, survival, treatment and outcomes in nations/populations hosting such registries [41, 42]; as revealed in some reports reviewed in this update [8, 12, 25]. Though there are cancer registries in only 54% of the 46 countries in sub-Saharan Africa; improved budgeting and infrastructure will improve the availability of data on cancer diagnosis, treatment, follow-up and survival [41, 43]; which can help in the estimation of cancer burden in sub-Saharan Africa and improve the policy and practice of the national cancer control programs which can improve the healthcare for patients with breast cancer in the years to come [41]. However, due to resource constraints in many countries of sub-Saharan Africa, hospital-based cancer registries can be established which can be a source of information on breast cancer (and other cancers) for the population-based cancer registries [43].

Finally, there is a need to ameliorate the financial burden of cancer prevention and care in sub-Saharan Africa; especially among the high-risk population and the vulnerable [42]. This is because the majority of healthcare financing in sub-Saharan Africa is out-of-pocket which places catastrophic healthcare expenditure on patients and caregivers [44, 45]. There is therefore the need increase include cancer screening and care in universal healthcare programs and policies of governments in sub-Saharan Africa [42].

8. Conclusion

Breast cancer has increasingly become a disease of global public health importance, and in particular in sub-Saharan Africa. It has been projected to increase to over 3 million by the year 2040. This might have been due to improved detection rates, awareness, and treatments globally; especially in higher-income countries. There appears to be an intra- and inter-country variation in breast cancer detection rates and mortality in sub-Saharan Africa. BRACA genes still appear to be commonly reported; though, some populations have commonly reported novel genes more than the former genes. Better organized screening programs, the establishment of a well-functioning cancer registry, and improved access and utilization of mammography and treatment services in resource-constrained regions can improve early presentation, reduce adverse breast cancer-related outcomes (including mortality) and help reduce future sub-Saharan African burden of breast Africa and the world.