Abstract 3516: Commercial gene expression tests for prostate cancer outcome risk in men of West African ancestry

Both incidence and mortality data show that the burden of prostate cancer (PrCa) is greater for African Americans (AA) than for European Americans (EAs), with AAs about 1.7 times more likely to be diagnosed with PrCa than EAs and about 2.4 times more likely to die of this disease. Molecular testing of prostate cancer tissue is increasingly being incorporated into patient management. Current National Comprehensive Cancer Network (NCCN) guidelines recommend three commercially available gene expression based tests for PrCa prognosis: Decipher (GenomeDX), Oncotype GPS (Genomic Health) and Prolaris (Myriad). All three of these tests were developed in predominantly EA patient populations and subsequent studies in AA patients have not included ancestry genotyping to assess genetic admixture. In a pilot study we used the Genomics Resource Information Database (GRID) to compare the research versions of these three commercial gene expression tests for PrCa outcome risk in 157 cancer positive biopsy cores from 55 patients. We also performed ancestry genotyping to estimate each patients European, West African and Native American Ancestry. The overall distribution of scores predicting average, higher than average and lower than average outcome risk differed for the three tests, with higher risk scores in 17%, 7% and 27% and lower risk scores in 69%, 73% and 43% of the cores for the Decipher, GPS and Prolaris tests, respectively. Interestingly, 25%, 37%, and 16% of 56 Cores with high risk pathology (grade group 3-5) were classified as low risk by the Decipher, GPS and Prolaris tests, respectively. In the 21 cores from men with > 70% WA ancestry, 100%, 80% and 30% of cores with intermediate and high risk pathology (grade group 2-5) were paradoxically classified as low risk by the research Decipher, GPS and Prolaris tests, respectively. These preliminary results are consistent with the evidence recently published by Creed et al (2019) suggesting that the currently available commercial genomic tests may underestimate prostate cancer outcome risk in AAs. Ancestry genotyping may be useful in rescaling genomic prostate cancer outcome risk tests that were developed in predominantly EA cohorts for use in AA patients. Reference: Creed JH et al. Cancer Epidemiol Biomarkers Prev, published online 2019. Citation Format: Sandra M. Gaston, Rick A. Kittles, Radka Stoyanova, Teresa M. Giret, Saba A. Ansari, Sanoj Punnen, Alan Pollack. Commercial gene expression tests for prostate cancer outcome risk in men of West African ancestry [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3516.