Abstract 4608: Racial differences in the distribution of prostate tumor biomarkers and treatment failure: The SCORE study

Abstract

Abstract Prostate cancer exhibits the greatest disparity in mortality between African American (AA) and European American (EA) men of any cancer in the US. The reasons for this disparity include access to care, screening patterns, and behavior. Biological differences may lead some AA men to have biologically aggressive tumors. Using the Study of Clinical Outcomes, Risk, and Ethnicity (SCORE) study, we identified prostate tumor tissues from men undergoing prostatectomy at the Hospital of the University of Pennsylvania between 1991-2008. Immunohistochemistry was undertaken on the FFPE tumors of 45 EA and 55 AA men (mean age: 59.1 years, range: 41-71). No statistically significant difference in marker phenotypes was observed for prevalence of TMPRSS2/ERG fusion proteins, or in staining intensity for PSMA or Rb. We observed statistically significant differences in marker phenotype for RACEMASE (EA Mean: 188.1 vs. AA Mean: 144.7, p = 0.004), c-myc (EA Mean: 54.7 vs. AA Mean: 21.6, p = 0.005), and AR (EA Mean: 192.1 vs. AA Mean: 136.5, p = 0.002). These data suggest that markers that have been reported to be associated with tumor aggressiveness differ between EA and AA men. We further evaluated whether these markers were associated with clinical outcome as measured by biochemical (PSA) failure (BF) after radical prostatectomy (RP). We observed 41 BF with a mean follow up of 32.6 months post-RP, compared with 68 non-BF with a mean follow up of 53.7 months post-RP. After adjusting for pathology tumor grade, only the presence of a TMPRSS2-ERG fusion protein was significantly associated with BF. We observed a significant interaction (p = 0.031) by race suggesting TMPRSS2-ERG fusions were less likely to be associated with BF in AA than in EA. These data suggest that TMPRSS2-ERG fusions may not be important predictors of prostate cancer outcomes in AA men as has been suggested in EA men. *These authors contributed equally to the work. Citation Format: Priti Lal*, Kosj Yamoah*, Amy Ziober, Amy Walker, Wenting Zhou, Elaine Spangler, Charnita Zeigler-Johnson, Michael Feldman, Timothy R. Rebbeck. Racial differences in the distribution of prostate tumor biomarkers and treatment failure: The SCORE study. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4608. doi:10.1158/1538-7445.AM2015-4608