Background: The detection of prostate cancer by screening for prostate-specific antigen (PSA) in serum is improved when age-specific reference ranges are used, but these ranges have been derived from white populations. We determined the distribution of PSA and age-specific reference ranges in black men both with and without prostate cancer.
Methods: From January 1991 through May 1995, we measured serum PSA in 3475 men with no clinical evidence of prostate cancer (1802 white and 1673 black) and 1783 men with prostate cancer (1372 white and 411 black). We studied the data as a function of age and race to determine the usefulness of measuring PSA in diagnosing prostate cancer.
Results: Serum PSA concentrations in black men (geometric mean in controls, 1.48 ng per milliliter; in patients, 7.46) were significantly higher than those in white men (geometric mean in controls, 1.33 ng per milliliter; in patients, 6.28). The values in the controls correlated directly with age. The area under the receiver-operating-characteristic curve was 0.91 for blacks and 0.94 for whites. If traditional age-specific reference ranges were used in screening black men, with the test specificity kept at 95 percent, 41 percent of cases of prostate cancer would be missed. For the test to have 95 percent sensitivity among black men, the following normal reference ranges should be used: for men in their 40s, 0 to 2.0 ng of PSA per milliliter (test specificity, 93 percent); for men in their 50s, 0 to 4.0 ng per milliliter (specificity, 88 percent); for men in their 60s, 0 to 4.5 ng per milliliter (specificity, 81 percent); and for men in their 70s, 0 to 5.5 ng per milliliter (specificity, 78 percent).
Conclusions: Serum PSA concentrations can be used to discriminate between men with prostate cancer and those without it among both blacks and whites. Over 40 percent of cases of prostate cancer in black men would not be detected by tests using traditional age-specific reference ranges, which maintain specificity at 95 percent. In this high-risk population, the alternative approach--maintaining sensitivity at 95 percent--may be used with acceptable decrements in specificity.