TMPRSS2:ERG Gene Fusions in Prostate Cancer of West African Men and Ameta-Analysis of Racial Differences

Abstract

The prevalence of TMPRSS2-ERG fusions in prostate cancer varies by race. However, such somatic aberration and its association with prognostic factors have neither been studied in a West African population nor been systematically reviewed in the context of racial differences. We used immunohistochemistry to assess ERG expression as the established surrogate of ERG fusion genes among 262 prostate cancer biopsies from the Ghana Prostate Study. Poisson regression with robust variance estimation provided prevalence ratios and 95% confidence intervals of ERG expression in relation to patients' characteristics. We found 47 of 262 (18%) prostate cancers were ERG-positive, and negative ERG staining was associated with higher Gleason score. We further conducted a systematic review and meta-analysis of TMPRSS2-ERG fusions in relation to race, Gleason score, and tumor stage, combining results from Ghana with 40 additional studies. Meta-analysis showed the prevalence of TMPRSS2-ERG fusions in prostate cancer to be highest in men of European descent (49%) followed by Asian (27%) and then African (25%). The lower prevalence of TMPRSS2-ERG fusions in men of African descent implies that alternative genomic mechanisms might explain the disproportionately high prostate cancer burden in such populations.