Relationships between prostate-specific antigen and prostate volume in black and white men with benign prostate biopsies

Objectives. To determine whether the higher age-adjusted serum prostate-specific antigen (PSA) levels in black compared with white men with no clinical evidence of prostate cancer reflect racial differences in relationships between PSA and prostate volume.Methods. The age, PSA, findings on digital rectal examination (DRE), prostate volume, and PSA density were assessed prospectively in 810 consecutive, evaluable men who underwent prostate biopsy for suspected cancer but who had benign histologic findings.Results. Among the black and white patients, there were significant differences in age (mean 67.2 ± 8.1 and 65.9 ± 7.7 years, respectively, P = 0.02), PSA (median 4.7 and 3.9 ng/mL, respectively, P <0.0001), prostate volume (median 41 and 36 mL, respectively, P = 0.004), and PSA density (median 0.11 and 0.08 ng/mL/mL, respectively, P = 0.005). Multiple linear regression analyses showed that black race was significantly associated with increased prostate volume when controlled for age (P = 0.02), with increased PSA when controlled for prostate volume and age (P = 0.002), and with increased PSA density when controlled for age (P = 0.007). When controlled for prostate volume, PSA was not significantly different in black and white men 50 to 59 years old but was significantly greater in black men 60 to 69 and 70 to 79 years old (P = 0.02 and 0.002, respectively).Conclusions. On a volume/volume basis, the benign prostatic tissue of black men appears to contribute more PSA to the circulating blood than does the benign prostatic tissue of white men, and the difference increases with advancing age. These phenomena provide a reasonable explanation for the age-adjusted racial differences in the PSA of men with no clinical evidence of cancer.