African-specific molecular taxonomy of prostate cancer

Abstract

Prostate cancer is characterized by considerable geo-ethnic disparity. African ancestry is a signifcant risk factor, with mortality rates across sub-Saharan Africa of 2.7-fold higher than global averages1 . The contributing genetic and non-genetic factors, and associated mutational processes, are unknown2,3 . Here, through whole-genome sequencing of treatment-naive prostate cancer samples from 183 ancestrally (African versus European) and globally distinct patients, we generate a large cancer genomics resource for sub-Saharan Africa, identifying around 2 million somatic variants. Signifcant African-ancestry-specifc fndings include an elevated tumour mutational burden, increased percentage of genome alteration, a greater number of predicted damaging mutations and a higher total of mutational signatures, and the driver genes NCOA2, STK19, DDX11L1, PCAT1 and SETBP1. Examining all somatic mutational types, we describe a molecular taxonomy for prostate cancer diferentiated by ancestry and defned as global mutational subtypes (GMS). By further including Chinese Asian data, we confrm that GMS-B (copy-number gain) and GMS-D (mutationally noisy) are specifc to African populations, GMS-A (mutationally quiet) is universal (all ethnicities) and the African–European-restricted subtype GMS-C (copy-number losses) predicts poor clinical outcomes. In addition to the clinical beneft of including individuals of African ancestry, our GMS subtypes reveal diferent evolutionary trajectories and mutational processes suggesting that both common genetic and environmental factors contribute to the disparity between ethnicities. Analogous to gene–environment interaction—defned here as a diferent efect of an environmental surrounding in people with diferent ancestries or vice versa—we anticipate that GMS subtypes act as a proxy for intrinsic and extrinsic mutational processes in cancers, promoting global inclusion in landmark studies.