Prostate Specific Antigen in Black and White Men After Hormonal Therapies for Prostate Cancer

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Abstract
Prostate cancer deaths usually result from proliferation of the androgen independent malignant phenotype, and in the United States the survival of black men with metastatic cancer is less favorable than that of white men. We compared prostate specific antigen (PSA) functions after hormonal therapies in men of both races to investigate potential differences in the biology of androgen independent cancer. The PSA nadir after gonadal androgen withdrawal was determined in 217 black and 188 white men with localized or metastatic cancer. The time to PSA elevation and PSA doubling time were determined in 62 black and 27 white men with biochemical relapse. Biochemical response to deferred flutamide treatment and flutamide withdrawal was assessed in 87 and 11 black and 30 and 10 white men, respectively. There were no significant racial differences in the PSA nadir when controlled for clinical stage and pretreatment PSA, or in PSA doubling time when controlled for clinical stage, PSA nadir and month of PSA elevation. The biochemical response to deferred flutamide therapy and flutamide withdrawal was the same in black and white men. The burden and growth rate of androgen independent cancer estimated from PSA functions after gonadal androgen withdrawal, and the impact of deferred antiandrogen therapy on the serum PSA are similar in black and white men. These findings suggest that racial differences in the biology of androgen independent carcinoma do not contribute to the inferior survival of black men with metastatic prostate cancer.