Men of African descent have the highest prostate cancer incidence and mortality rates. Writes Morgan Morris.
Now a major genome-wide association study (GWAS) that looks at complete sets of DNA or genomes to find genetic variations that can be linked to particular diseases – is beginning to explain why.
The research, conducted by the international Men of African Descent and Carcinoma of the Prostate (MADCaP) network, draws on bio-samples from some 7,500 participants from Ghana, Nigeria, Senegal, South Africa and Uganda.
The study included nearly 4,000 cases of prostate cancer.
The study aims to fill a crucial gap in the understanding of prostate cancer among men of African descent.
While factors like poverty and education levels have been well explored, genetic susceptibility has been under-researched among men of African descent.
And particularly in Africa, an area which has been largely overlooked.
Based on findings from the United States and the Caribbean, men of African descent are disproportionately affected by prostate cancer.
Scientists also want to understand an increase in prostate cases of about 60 percent over just the past 15 years in Southern Africa.
The MADCaP study identified three gene loci with strong associations to prostate cancer incidence among African men.
The researchers were particularly looking for associations with aggressive cancer.
The loci are called 8q24.21, 6q22.1, and 11q13.3, all gene regions with known associations to other forms of cancers. Within the three regions, the study identified 15 ‘private alleles’ that are genetic variants specific to African men.
But the picture is not uniform across Africa.
The researchers found that the importance of these three loci and the associated genetic variants differed significantly across West Africa, East Africa and South Africa.
This, they conclude, is the result of evolutionary factors.
The findings could contribute to explaining the elevated rates of prostate cancer found across the African diaspora, including African American men, and could help shape models for predicting cancer risk.
It also illustrates why research involving African populations is crucial, as these associations would not have been detected in studies of non-African people alone, explain the authors.
The long-term goal is to develop tools that would allow estimating the risk of aggressive cancer for individual patients, explains MADCaP team member Carl Chen, a medical scientist with the Sydney Brenner Institute for Molecular Bioscience at the University of the Witwatersrand, South Africa.