RELATIONSHIP OF DEMOGRAPHIC AND CLINICAL FACTORS TO FREE AND TOTAL PROSTATE-SPECIFIC ANTIGEN EDWARD P. GELMANN, DAVID CHIA, PAUL F. PINSKY, GERALD L. ANDRIOLE, E. DAVID CRAWFORD, DOUGLAS REDING, RICHARD B. HAYES, BARNETT S. KRAMER, DAVID L. WOODRUM, JOHN K. GOHAGAN, AND DAVID L. LEVIN, FOR THE PLCO SCREENING TRIAL INVESTIGATORS ABSTRACT Objectives. To characterize the role of demographic and clinical parameters in the measurements of prostate-specific antigen (PSA), free PSA (fPSA), and percent free PSA (%fPSA). Methods. This was a cohort study of volunteers to a randomized screening trial. A central laboratory determined PSA and fPSA for the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. A baseline evaluation of free and total PSA was done for 7183 white, black, Asian, Hispanic, and other male volunteers, aged 55 to 74 years. Comparisons were made across racial and ethnic groups and across a set of clinical parameters from a baseline questionnaire. Results. The median levels of serum PSA were less than 2.1 ng/mL in each age-race grouping of the study participants. The levels of free and total PSA were higher in black (n = 868, 12%) participants than in white (n = 4995, 70%) and Asian (n = 849, 11.8%) participants. Individuals who identified themselves as ethnically Hispanic (n = 339, 4.7%) had median PSA levels higher than whites who were not Hispanic. The free and total PSA levels increased with age, particularly among men 70 to 74 years old. However, the %fPSA levels showed less variation among the four racial groups or by age. The free and total PSA levels were higher among those who had a history of benign prostatic disease. Conclusions. Demographic (age and race/ethnicity) and clinical (history of benign prostatic disease) vari- ables had a moderate effect on the measures of PSA and fPSA and very little effect on %fPSA. UROLOGY 58: 561–566, 2001. © 2001, Elsevier Science Inc. T he measurement of serum prostate-specific an- tigen (PSA) is a widely used test for the screen- ing and management of prostate cancer. The use of PSA levels to screen for prostate cancer has not yet been shown to affect cause-specific mortality in a randomized trial. 1 During the past decade, a down- ward shift has occurred in the stage predominance of newly diagnosed prostate cancers, and there has been a suggestion of improved mortality that may be due to the use of PSA screening. 2 The sensitivity and specificity of PSA screening depends to some degree on the upper limit used for a threshold PSA This study was funded through contracts from the National Can- cer Institute to individual participating centers of the National Cancer Institute Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. The PSA assay reagents were supplied by Beckman Coulter, Inc. Beckman Coulter is a partial sponsor of the PLCO Screening Trial by virtue of providing the PSA and fPSA test kits for this study. The tests were performed at UCLA, not Beckman Coulter. From the Lombardi Cancer Center, Georgetown University, Washington, DC; University of California, Los Angeles, Tissue Typing Laboratory, Los Angeles, California; Early Detection Re- search Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, Maryland; Division of Urology, Washington University, St. Louis, Missouri; Urologic Oncology, University of Colorado Health Sciences Center, Denver, Colorado; Department of Hematology/Oncology, Marshfield Clinic, Marshfield, Minne- sota; Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; and Office of Medical Applications of Research, National Institutes of Health, Bethesda, Maryland; Beckman Coulter, Inc., San Diego, California; and Biometry Research Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, Maryland Reprint requests: Edward P. Gelmann, M.D., Lombardi Cancer Center, Georgetown University, 3800 Reservoir Road, NW, Washington, DC 20007-2197 Submitted: March 14, 2001, accepted (with revisions): May 23, 2001 ADULT UROLOGY © 2001, ELSEVIER SCIENCE INC. 0090-4295/01/$20.00 ALL RIGHTS RESERVED PII S0090-4295(01)01305-X 561