Evaluating the impact of African American ancestry among men with localized prostate cancer treated with radical prostatectomy.

Abstract

41 Background: Prostate cancer (PC) is the most common male malignancy. Prior data has suggested that African American (AA) men present with more aggressive disease relative to men of other ancestries. Here, we examined the effects of ancestry on clinical and molecular measures of disease aggressiveness as well as pathologic outcomes in men treated with radical prostatectomy (RP) for localized PC. Methods: Data was collected from patients undergoing RP at the Ochsner Clinic from 2006 to 2011. Formalin−fixed paraffin embedded biopsy tissue was analyzed for the RNA expression of 31 cell cycle progression (CCP) genes and 15 housekeeping genes to obtain a CCP score (a validated molecular measure of PC aggressiveness). Cancer of the Prostate Risk Assessment (CAPRA) scores were also determined based on clinicopathologic features at the time of diagnosis. Clinical (Gleason score, tumor stage, CAPRA score) and molecular (CCP score) measures of disease aggressiveness were compared based on ancestry (AA versus non−AA). Cox proportional hazards models were used to test association of ancestry to biochemical recurrence (BCR) and progression to metastatic disease. Fisher’s exact and Wilcoxon rank sum tests were used to compare ancestries. Results: A total of 384 patients were treated with RP, including 133 (34.8%) AA men. At the time of diagnosis, the median age was 62 years (interquartile range (IQR) 56, 66) and PSA was 5.4 ng/mL (IQR 4.2, 7.6). When compared by ancestry, there were no significant differences in biopsy Gleason score (p = 0.26), clinical stage (p = 0.27), CAPRA score (p = 0.58), or CCP score (p = 0.87). In addition, there was no significant difference in the risk of BCR between ancestries (p = 0.55). Only non−AA men progressed to metastatic disease within the ten years of follow−up. Conclusions: Contrary to prior reports, these data appears to indicate that men of AA ancestry do not necessarily present with or develop a more biologically aggressive form of PC. Although these data represents only one institution’s experience, it contains a highly robust AA population compared to prior reports. Further research is required to account for the discrepancy in the previously published literature.