Mapping Cancer in Africa: A Comprehensive and Comparable Characterization of 34 Cancer Types Using Estimates From GLOBOCAN 2020

Abstract

Objective: Cancer incidence and mortality rates in Africa are increasing, yet their geographic distribution and determinants are incompletely characterized. The present study aims to establish the spatial epidemiology of cancer burden in Africa and delineate the association between cancer burden and the country-level socioeconomic status. The study also examines the forecasts of the cancer burden for 2040 and evaluates infrastructure availability across all African countries.

Methods: The estimates of age, sex, and country-specific incidence and mortality of 34 neoplasms in 54 African countries, were procured from GLOBOCAN 2020. Mortality-to-incidence ratio (MIR) was employed as a proxy indicator of 5-year survival rates, and the socioeconomic development of each country was measured using its human development index (HDI). We regressed age-standardized incidence rate (ASIR), age-standardized mortality rate (ASMR), and MIR on HDI using linear regression model to determine the relationship between cancer burden and HDI. Maps were generated for each cancer group for each country in Africa. The data about the cancer infrastructure of African countries were extracted from the WHO Cancer Country Profiles.

Results: In Africa, an estimated 1.1 million new cases [95% uncertainty intervals (UIs) 1.0 - 1.3 million] and 711,429 [611,604 - 827,547] deaths occurred due to neoplasms in 2020. The ASIR was estimated to be 132.1/100,000, varying from 78.4/100,000 (Niger) to 212.5/100,000 (La Réunion) in 2020. The ASMR was 88.8/100,000 in Africa, ranging from 56.6/100,000 in the Republic of the Congo to 139.4/100,000 in Zimbabwe. The MIR of all cancer combined was 0.64 in Africa, varying from 0.49 in Mauritius to 0.78 in The Gambia. HDI had a significant negative correlation with MIR of all cancer groups combined and main cancer groups (prostate, breast, cervical and colorectal). HDI explained 75% of the variation in overall 5-year cancer survival (MIR). By 2040, the burden of all neoplasms combined is forecasted to increase to 2.1 million new cases and 1.4 million deaths in Africa.

Conclusion: High cancer mortality rates in Africa demand a holistic approach toward cancer control and management, including, but not limited to, boosting cancer awareness, adopting primary and secondary prevention, mitigating risk factors, improving cancer infrastructure and timely treatment.

Keywords: Africa; GLOBOCAN; cancer burden; incidence; mapping; mortality; spatial epidemiology.

Figure 1

Country-specific ASIR. Cancer ASIR per 100,000 for each country in Africa. ASIR, Age-standardized Incidence Rate; HL, Hodgkin Lymphoma; NHL, Non-Hodgkin Lymphoma; CNS, Central Nervous System.

Figure 2

Country-specific ASMR. Cancer ASMR per 100,000 for each country in Africa. ASMR, Age-standardized Mortality Rate; HL, Hodgkin Lymphoma; NHL, Non-Hodgkin Lymphoma, CNS, Central Nervous System.

Figure 3

Country-specific MIR. Cancer MIR (proxy for 5-year survival rate) for each country in Africa. MIR, Mortality-to-incidence ratio; HL, Hodgkin Lymphoma; NHL, Non-Hodgkin Lymphoma; CNS, Central Nervous System.

Figure 4

Age-specific burden of all neoplasms in Africa, 2020. (A) Absolute numbers and (B) Rates per 100,000 people. Data source: GLOBOCAN 2020 (International Agency for Research on Cancer).

Figure 5

Bivariate relationship between Age-standardized rates, MIR and HDI. ASIR, Age-standardized incidence rate (cases per 100,000); ASMR, Age-standardized mortality rate (deaths per 100,000); MIR, Mortality-to-Incidence Ratio; HDI, Human Development Index. Data source: GLOBOCAN 2020 (International Agency for Research on Cancer). The dots on scatter plot are inflated as per respective ASIR and marked as per country's ISO-3 code. The data of HDI is procured from United Nations Development Program. (A) ASIR vs. HDI. (B) ASMR vs. HDI. (C) MIR vs. HDI.

Figure 6

Comparison of cancer burden of all cancer groups in 2020 and forecasted values in 2040 (A) Incidence and (B) Deaths. Data source: GLOBOCAN 2020 (International Agency for Research on Cancer).