Abstract
IMPORTANCE: Prostate cancer in Black men compared with White men may be more sensitive to radiation therapy resulting in better outcomes in equal-access settings. The outcomes of androgen-deprivation therapy (ADT) vs radiation therapy itself remains uncharacterized. OBJECTIVES: To quantify any outcome modification by receipt of ADT on the association between Black race and prostate cancer outcomes following radiation therapy. DESIGN, SETTING, AND PARTICIPANTS: This was a retrospective, nationwide cohort study of Black and White patients treated in the US Veterans Healthcare system between 2000 and 2020 receiving definitive radiation for localized prostate cancer. Data were analyzed from January 2000 to December 2020. EXPOSURE: Patient self-identified race and use of ADT defined as any gonadotrophin-releasing hormone agonist or antagonist prescription within 6 months of radiation. MAIN OUTCOMES AND MEASURES: Biochemical recurrence (BCR) from time of completion of radiation therapy (prostate-specific antigen nadir plus 2 ng/mL) and development of metastatic disease or prostate cancer mortality (PCSM) from time of recurrence. RESULTS: A total of 26 542 patients (8716 Black men with median [IQR] age of 64 [59-69] years and 17 826 White men with median [IQR] age of 67 [62-72] years) received definitive radiation therapy for nonmetastatic prostate cancer and had complete staging and follow-up data. A total of 5144 patients experienced BCR (3384 White and 1760 Black patients). The cumulative incidence of BCR at 10 years was not significantly different between Black and White men (1602 [22.14%] vs 3099 [20.13%], respectively) with multivariable hazard ratio (HR) of 1.03 (95% CI, 0.97-1.09; P = .33). In men receiving ADT, Black men had an HR for BCR of 0.90 (95% CI, 0.82-0.99; P = .03) compared with White men, and in men not receiving ADT, Black men had an HR of 1.13 (95% CI, 1.05-1.22; P = .002). Black race was associated with a decreased risk of developing metastatic disease (HR, 0.90; 95% CI, 0.82-0.98; P = .02) or PCSM (subdistribution HR, 0.72; 95% CI, 0.63-0.82; P < .001) from time of biochemical recurrence. CONCLUSIONS AND RELEVANCE: Black patients treated with radiation appear to specifically benefit from the addition of ADT with regard to biochemical control. Additionally, BCR in Black men results in a lower rate of metastatic disease and death from prostate cancer. Future analyses of radiosensitivity in Black men should evaluate for the possibility of outcome modification by ADT.