Breast cancer in sub-Saharan Africa: The current state and uncertain future

Abstract

Breast cancer is the commonest cause of global cancer-related deaths in women and a public health burden in sub-Saharan Africa (SSA). Although the disease incidence in SSA seems lower, mortality rates are disproportionately high in comparison to high-income countries. The global disease burden is growing, with SSA reporting the majority of cases; however, the dearth of information results in insufficient data which is barely representative of the actual disease burden in this population. Future incidence predictions assign the subregion with a majority of the cases and associated deaths. Breast cancer presents with racial and ethnic variations, and available evidence suggests geographical diversity and persistent risk factors that have barely been explored in SSA. Breast cancer is a complex genetic disease, but the genetic risk factors in the extant African population, which is the most genetically diverse population, is scant and of low quality. This review focuses on the burden, prevalence, detection, treatment, survival, biology, as well as risk factors, and reinforces the need for breast cancer-associated risk factor investigation and population-specific studies in SSA.

Keywords: Breast cancer; burden; genetic diversity; population-specific research; risk factors; sub-Saharan Africa.

Figure 1.

Sub-Saharan Africa. West Africa: Mauritania, Senegal, Gambia Guinea-Bissau, Guinea, Sierra Leone, Liberia, Côte d'Ivoire, Ghana, Togo, Benin, Burkina Faso, Nigeria, Niger, Mali, and Cabo Verde; Central Africa: Cameroon, Central African Republic, Chad, Democratic Republic of the Congo, Equatorial Guinea, Gabon, and Sao Tomé and Principe; Southern Africa: South Africa, Lesotho, Namibia, Swaziland, and Botswana; East Africa: Tanzania, Kenya, Uganda, Rwanda, Burundi, South Sudan, Mozambique, Madagascar, Malawi, Zambia. Zimbabwe, Mauritius, Comoros, Djibouti, Ethiopia, Eritrea, Seychelles, Somaliland, Somalia, and Réunion. The figure was drawn using geographic heatmap in excel. (A color version of this figure is available in the online journal.)

Figure 2.

The 2018 global breast cancer Mortality versus Incidence in women. Incidence in the African countries (purple dots) seems low; however, mortalities are relatively high. Europe reports the highest incidence and LAC, the highest mortality. The Republic of Gambia recorded the lowest incidence and mortality (6.9, 4) and Mauritius, the highest (69.6, 21.8) in Africa. This graph was generated using excel and data from the GLOBOCAN (http://gco.iarc.fr/) interactive observatory, and includes data from all the 54 African countries. ASR (W): age-standardized rate (World); LAC (Latin America and the Caribbean). (A color version of this figure is available in the online journal.)

Figure 3.

The estimated number of new cancer cases in females in 2020. Breast cancer was the most diagnosed cancer and cause of cancer-related death in females in 2020. Africa reported 531,086 (74.3/100,000) new cases. Africa recorded a mortality of 85,787 (19.4/100,000), compared to Europe with 141,765 (14.8/100,000). In comparison to Europe, the associated deaths recorded in Africa seems disproportionate to the incidence reported. This data was generated using the GLOBOCAN 2020 data and interactive observatory. NHL: non-hodgkin lymphoma. (A color version of this figure is available in the online journal.)

Figure 4.

The 2019 World Bank global landscape of poor countries as per GNI-PPP ($). The African countries ranged from $727 (Burundi) to $19,057 (Gabon), however, out of the four low-income countries, three (Burundi, Central Africa Republic and Democratic republic of Congo) are in SSA. The heatmap was generated using power-user in excel and countries investigated by the African Strategies for Advancing Pathology Group Members. Countries in grey did not have data at the time of generation. USD (US dollar); GNI-PPP (Gross National Income based on purchasing-power-parity). (A color version of this figure is available in the online journal.)

Figure 5.

The predicted proportion of the 2012 global postmenopausal breast cancer cases among women attributable to body mass index (BMI). This prediction hinges on the assumption that the average population-level BMI remained constant since 1982. Per this record, SSA recorded the lowest attributable cases, probably due to underreporting. Data was obtained from GLOBOCAN 2012, Graph production: IARC World Health Organization. (A color version of this figure is available in the online journal.)