Racial Disparity in Prostate Cancer-Specific Mortality for High-Risk Prostate Cancer: A Population-Based Study

INTRODUCTION Race may be a significant factor that influences prostate cancer (PCa) survival, with the Asian (AsA) race being associated with better outcomes compared to African American (AA) and Non-Hispanic Whites (NHW). This study evaluates race-dependent variation in PCa-specific mortality (PCSM) associated with radiation dose-escalation exemplified by external beam radiotherapy (EBRT) with a brachytherapy (BT) boost in Gleason score 8-10 PCa. METHODS 28,956 men diagnosed with clinically localized PCa and Gleason score 8-10 from 2004-2013 who received EBRT, EBRT with a BT boost, or radical prostatectomy (RP) were identified using the Surveillance, Epidemiology, and End Results (SEER) database. PCSM adjusted for age, diagnosis year, T-stage, Gleason scores, and treatment modalities was compared between races using a competing risk model that accounted for other-cause mortality (OCM). RESULTS Compared to AsA, AA and NHW are associated with significantly increased PCSM with adjusted hazard ratios (AHR) of 2.295 and 1.989, respectively (p < 0.001 for both). In a subgroup analysis stratified by race, dose-escalation exemplified by EBRT with a BT boost in both AA and AsA failed to demonstrate a significant difference in PCSM compared to EBRT alone (p = 0.530 and 0.990, respectively), while a significant PCSM decrease was seen in NHW (p = 0.006). CONCLUSIONS Dose-escalation exemplified by EBRT with a BT boost had no significant effect on PCSM of AsA and AA, while it did decrease PCSM amongst NHW. Further evaluation of race as a factor impacting PCSM in the era of dose-escalation is needed in the prospective setting.