Black Men Have Lower Rates Than White Men of Biochemical Failure with Primary Androgen-Deprivation Therapy

Abstract

Black men have a higher incidence of advanced stage at diagnosis and mortality from prostate cancer than do men in other racial groups. Given that androgen-deprivation therapy (ADT) is one of the mainstays of treatment for advanced prostate cancer, we investigated the development of biochemical failure, or recurrence of elevated prostate-specific antigen (PSA) levels, among different races in men receiving ADT. Patients with prostate cancer who received ADT in the Kaiser Permanente Southern California Cancer Registry between January 2003 and December 2006 were eligible for inclusion in our study. Patients who had prior treatment for their cancer with surgery or radiation were excluded. Treatment failure was defined as an increase in PSA of >2 ng/mL from PSA nadir, with no subsequent decrease in PSA. We compared the biochemical failure rate in white patients to those in black, Hispanic, and Asian/other patients. The Cox proportional hazards regression model was used to estimate hazards ratios. Our study population consisted of 681 patients: 416 (61%) were white; 107 (16%) were black; 107 (16%) were Hispanic; and 51 (7%) were Asian or another race. After we controlled for all demographic variables and for variables related to prostate cancer, blacks were the only group with a lower risk of treatment failure compared with whites. The hazard ratios for treatment failure were as follows: black versus white, 0.66 (p = 0.03); Hispanic versus white, 1.00 (p = 0.8); Asian/other race versus white, 1.5 (p = 0.1). In this multivariate analysis, pretreatment PSA level and cancer stage were the only other variables associated with a higher risk of treatment failure. Among patients receiving ADT as primary monotherapy for prostate cancer, blacks may have a lower rate of biochemical failure compared with whites. Although the etiology of this finding is unclear, it suggests the possibility that prostate cancer in black men may be more androgen sensitive than it is in white men.