African American men have among the highest prostate cancer incidence rates in the world yet rates among their African counterparts are unclear. In this paper, we compared reported rates among black men of Sub-Saharan African descent using data from the International Agency for Research on Cancer (IARC) and the National Cancer Institute Surveillance, Epidemiology, and End Results Program for 1973–2007. Although population-based data in Africa are quite limited, the available data from IARC showed that rates among blacks were highest in the East (10.7–38.1 per 100,000 man-years, age-adjusted world standard) and lowest in the West (4.7–19.8). These rates were considerably lower than those of 80.0–195.3 observed among African Americans. Rates in Africa increased over time (1987–2002) and have been comparable to those for distant stage in African Americans. These patterns are likely due to differences between African and African American men in medical care access, screening, registry quality, genetic diversity, and Westernization. Incidence rates in Africa will likely continue to rise with improving economies and increasing Westernization, warranting the need for more high-quality population-based registration to monitor cancer incidence in Africa.
African American men have among the highest reported prostate cancer rates in the world [
We used prostate cancer incidence data for Africa from publications of the International Agency for Research on Cancer (IARC;
Age-adjusted prostate cancer incidence ratesa per 100,000 man-years, 95% confidence intervals (CIs), percent microscopically verified, and percent reported by death certificate only in Sub-Saharan Africa and the United States, 1973–2007.
Location and/or race | Source | Time period | No. cases | Incidence ratea | 95% CIb | Microscopically verified (%) | Death certificate only (%) |
Blantyre, Malawi | Cancer in Africa | 2000-2001 | 30 | 10.7 | 6.9–14.5 | 47 | NK |
Eldoret, Kenya | Cancer in Africa | 1998–2000 | 54 | 16.8 | 12.3–21.3 | 30 | NK |
Harare, Zimbabwe: African | CI5 VII | 1990–1992 | 112 | 28.3 | 22.5–43.1 | 64 | 9 |
CI5 VIII | 1993–1997 | 251 | 30.7 | 26.5–34.9 | 56 | 15 | |
CI5 IX | 1998–2002 | 418 | 38.1 | 34.1–42.1 | 63 | 15 | |
Kyadondo, Uganda | CI5 VII | 1991–1993 | 86 | 27.7 | 21.6–33.8 | 67 | NK |
CI5 VIII | 1993–1997 | 215 | 37.1 | 31.7–42.5 | 77 | 0 | |
CI5 IX | 1998–2002 | 262 | 37.6 | 32.8–42.4 | 58 | NK | |
Namibia | Cancer in Africa | 1995–1998 | 352 | 21.8 | 19.5–24.1 | 97 | NK |
South Africa: blacks | Cancer in Africa | 1989–1992 | 3432 | 14.3 | 13.8–14.8 | 100 | NK |
Swaziland | Cancer in Africa | 1996–1999 | 153 | 21.5 | 18.1–24.9 | 24 | NK |
Bamako, Mali | CI5 VI | 1987–1989 | 21 | 6.3 | 3.5–9.1 | 5 | 5 |
CI5 VII | 1988–1992 | 33 | 5.2 | 3.4–7.0 | 21 | 6 | |
CI5 VIII | 1994–1996 | 29 | 7.6 | 4.8–10.4 | 55 | 3 | |
Conakry, Guinea | Cancer in Africa | 1996–1999 | 62 | 9.7 | 7.3–12.1 | 45 | NK |
Ibadan, Nigeria | Cancer in Africa | 1998–1999 | 115 | 19.8 | 16.2–23.4 | 70 | NK |
Niamey, Niger | Cancer in Africa | 1993–1999 | 41 | 10.8 | 7.5–14.1 | 34 | NK |
The Gambia | CI5 VIII | 1997-1998 | 20 | 4.7 | 2.5–6.9 | 20 | NK |
United States | |||||||
Blacks | NCI-SEER | 1973–1977 | 2666 | 80 | 77.0–83.1 | 93 | 1 |
NCI-SEER | 1978–1982 | 3783 | 89.8 | 86.8–92.6 | 95 | 1 | |
NCI-SEER | 1983–1987 | 4754 | 100.0 | 97.1–102.8 | 96 | 1 | |
NCI-SEER | 1988–1992 | 7511 | 143.3 | 140.1–146.6 | 97 | 0 | |
NCI-SEER | 1993–1997 | 10853 | 195.9 | 191.6–199.1 | 96 | 1 | |
NCI-SEER | 1998–2002 | 11940 | 192.9 | 186.6–193.7 | 97 | 1 | |
NCI-SEER | 2003–2007 | 12618 | 172.8 | 169.8–176.0 | 98 | 1 | |
Whites | NCI-SEER | 1973–1977 | 24212 | 47.9 | 47.3–48.5 | 94 | 1 |
NCI-SEER | 1978–1982 | 31389 | 54.8 | 54.1–55.3 | 95 | 1 | |
NCI-SEER | 1983–1987 | 39492 | 63.5 | 62.8–64.0 | 97 | 0 | |
NCI-SEER | 1988–1992 | 68863 | 104.3 | 103.3–104.9 | 96 | 1 | |
NCI-SEER | 1993–1997 | 73687 | 111.8 | 110.5–112.2 | 97 | 1 | |
NCI-SEER | 1998–2002 | 80100 | 116.9 | 115.1–116.8 | 97 | 1 | |
NCI-SEER | 2003–2007 | 80022 | 107.0 | 106.2–107.8 | 98 | 1 |
CI: confidence interval; NK: not known; CI5: Cancer Incidence in Five Continents; NCI-SEER: National Cancer Institute’s Surveillance, Epidemiology, and End Results Program: nine registries.
aAll rates are age adjusted to Segi’s world standard population [
b95% CIs were obtained directly from CI5, were estimated for data from the Cancer in Africa publication by multiplying the standard error (incidence rate divided by the square root of the total number of cases) by 1.96, and adding to and subtracting from the incidence rate to obtain the upper and lower bounds, respectively, or were provided by SEER*Stat.
For comparison with these African data, we calculated rates for US Blacks and Whites from the National Cancer Institute (NCI) Surveillance, Epidemiology, and End Results (SEER) Program for the original nine registries combined using SEER*Stat version 7.0.4 (
We examined trends for SEER during 1973–2007 and for three African registries that reported rates for at least three time points during that time period. We used log scales to plot the rates such that a slope of 10 degrees portrayed a change of 1% per year (Origin version 8.0; OriginLab Corporation, Northampton, Ma, USA) [
Among the African countries, the number of cases ranged from 20 in The Gambia (1997-1998) to 3,432 in South African Blacks (1989–1992) (Table
Reasons for the large variation of prostate cancer in blacks within the African continent and the observed East-West disparity are unclear but are likely related to differences in medical care access, registry quality, including completeness of case ascertainment and estimates of populations at risk, screening practices, as well as lifestyle factors in subpopulations [
Quality of the medical care systems and registries also may have a substantial impact on the completeness and accuracy of the reported incidence rates. Availability of pathology services (reflected by percent of cases microscopically verified; Table
Unlike the US where increasing and widespread use of prostate-specific antigen (PSA) screening contributed to the rapid rise in incidence during the early 1990s [
Age-adjusted (Segi’s world standard) prostate cancer incidence in Sub-Saharan Africa and the United States, 1973–2007. (a) Africa: total prostate cancer rates from registries in three African cities; the populations of both Mali and Uganda were >95% black, and the rates for Zimbabwe were specific for black Africans. US: SEER nine registries combined for blacks (b) and whites (c): total and by SEER historical stage: nondistant and distant. All rates are for 3–5 year time periods (see Table
Similar to reasons given above for the geographic variation in rates within Africa, it is likely that improved health care systems and better ascertainment and reporting of cases may contribute to the rising rates in Africa [
Considering that the level of Westernization in Africa is still much lower than that in the US, the observation that total incidence rates in East Africa (Zimbabwe and Uganda), even in the earlier time period, were slightly higher than those of distant stage disease among African Americans is consistent with recent findings from genome-wide association studies (GWAS) showing that genetics are an important factor in prostate cancer. Recent GWAS have linked over 30 independent genetic loci to higher risks of prostate cancer in populations of European descent, including multiple loci in chromosome 8q24 [
In a previous publication, Parkin et al. [
Although data are limited, our analysis showed that (1) reported total prostate cancer incidence in Africa is lower than that among African Americans; (2) rates vary substantially (8-fold) within Sub-Saharan Africa, with rates lowest in the West and highest in the East; (3) total prostate cancer rates in Africa are similar to distant-stage disease rates in the US; (4) incidence appears to be rising in several African countries. It should be noted that when making inferences from these findings, consideration should be given to limitations in data quality. Undoubtedly, with improved economies and clinical diagnosis as well as increased Westernization, incidence rates in Africa are likely to continue to rise. Therefore, a high priority in this population should be the implementation of high-quality population-based cancer registration to monitor incidence rates in Africa and to develop effective cancer prevention strategies.
This work was supported by the Intramural Research Program, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health. Lisa W. Chu is supported by the Cancer Prevention Fellowship Program, Office of Preventive Oncology, National Cancer Institute, National Institutes of Health. The authors thank Dr. B. J. Stone for her expert editorial assistance and Mr. D. Carreon and Mr. D. Check for their assistance with graphics.