Racial Comparisons of Prostate Cancer Outcomes in a Unique Military Patient Population Post-Definitive External Beam Radiation Therapy

Abstract

The United States military represents a unique patient population to study prostate cancer outcomes due to a large percentage of minorities, increased level of fitness and universal access to care. We analyzed our military institutional prostate cancer outcomes in a young cohort after definitive external beam radiation therapy, and observed better than expected biochemical free survival (BFS) and overall survival (OS) outcomes for minorities, compared to historical controls. Minority outcomes were also equivalent to outcomes of Caucasians in our cohort. Patients who received definitive external beam radiation therapy (EBRT) were eligible (1995-2012). 120 patients with a median age of 63 were included in our cohort. 57% of patients were Caucasian, 43% were minorities including 23% African-American patients. Hazard ratios (HR) and 95% confidence intervals (95% CI) were used to assess the association between OS and BFS among racial groups (Caucasian, African American/Other) stratified by NCCN risk groups (low, intermediate, high). Patients in the high and intermediate risk groups had a higher risk of 10-year PSA failure compared to subjects in the low risk group (HR=10.93, 95% CI=2.32-51.61; HR=4.95, 95% CI=1.03-23.85, respectively). Patients in the high risk group had an increased risk of death compared to patients in the low risk group (HR=2.84, 95% CI=1.30-6.24). Among low, intermediate, and high risk groups, 3.7%, 20.6%, and 30.8% of patients experienced PSA failure, respectively. All-cause mortality occurred in 20.0%, 33.3%, and 51.7% of low, intermediate, and high risk groups, respectively. Stratified by risk group, minority patients did not have a significantly different hazard of 10-year PSA failure compared to Caucasian subjects (low risk group: HR=0.70, 95% CI=0.15-3.32; intermediate risk group: HR=1.90, 95% CI=0.59-6.08; high risk group: HR=0.53, 95% CI=0.19-1.47). Minority patients did not have a significantly different hazard of mortality compared to Caucasian subjects (low risk group: HR=2.23, 95% CI=0.14-36.74; intermediate risk group: HR=0.45, 95% CI=0.09-2.32; high risk group: HR=1.13, 95% CI=0.27-4.75). Our minority patients had similar BFS and OS outcomes compared to their Caucasian counterparts, and better than expected outcomes compared to historical controls. The military’s unique health care system with universal access to care and increased level of fitness may explain why our minority patients had improved outcomes. The influence of universal access to care upon treatment outcomes may be explained through increased prostate cancer risk assessment, improved rates of PSA screening, more reliable follow-up, and diagnosis at an earlier stage of disease, which all portend better outcomes. Further investigation is warranted regarding whether improved access to care may ameliorate racial disparities in prostate cancer outcomes.