Prostate cancer genetic risk and associated aggressive disease in men of African ancestry.

African ancestry is a significant risk factor for prostate cancer and advanced disease. Yet, genetic studies have largely been conducted outside the context of Sub-Saharan Africa, identifying 278 common risk variants contributing to a multiethnic polygenic risk score, with rare variants focused on a panel of roughly 20 pathogenic genes. Based on this knowledge, we are unable to determine polygenic risk or differentiate prostate cancer status interrogating whole genome data for 113 Black South African men. To further assess for potentially functional common and rare variant associations, here we interrogate 247,780 exomic variants for 798 Black South African men using a case versus control or aggressive versus non-aggressive study design. Notable genes of interest include HCP5, RFX6 and H3C1 for risk, and MKI67 and KLF5 for aggressive disease. Our study highlights the need for further inclusion across the African diaspora to establish African-relevant risk models aimed at reducing prostate cancer health disparities.

Linking African ancestral substructure to prostate cancer health disparities.

Prostate cancer (PCa) is a significant health burden in Sub-Saharan Africa, with mortality rates loosely linked to African ancestry. Yet studies aimed at identifying contributing risk factors are lacking within the continent and as such exclude for significant ancestral diversity. Here, we investigate a series of epidemiological demographic and lifestyle risk factors for 1387 men recruited as part of the multi-ethnic Southern African Prostate Cancer Study (SAPCS). We found poverty to be a decisive factor for disease grade and age at diagnosis, with other notably significant PCa associated risk factors including sexually transmitted diseases, erectile dysfunction, gynaecomastia, and vertex or complete pattern balding. Aligned with African American data, Black ethnicity showed significant risk for PCa diagnosis (OR = 1.44, 95% CI 1.05-2.00), and aggressive disease presentation (ISUP ≥ 4: OR = 2.25, 95% CI 1.49-3.40). New to this study, we demonstrate African ancestral population substructure associated PCa disparity, observing increased risk for advanced disease for the southern African Tsonga people (ISUP ≥ 4: OR = 3.43, 95% CI 1.62-7.27). Conversely, South African Coloured were less likely to be diagnosed with aggressive disease overall (ISUP ≥ 3: OR = 0.38, 95% 0.17-0.85). Understanding the basis for PCa health disparities calls for African inclusion, however, lack of available data has limited the power to begin discussions. Here, focusing on arguably the largest study of its kind for the African continent, we draw attention to the contribution of within African ancestral diversity as a contributing factor to PCa health disparities within the genetically diverse region of southern Africa.