Percent free prostate specific antigen and cancer detection in black and white men with total prostate specific antigen 2.5 to 9.9 NG./ML.

Purpose: The ratio of free-to-total prostate specific antigen (PSA), or per cent free PSA, is a useful adjunct to total PSA for estimating the risk of prostate cancer when total PSA is 2.5 to 9.9 ng./ml. Relationships between cancer detection and total PSA are influenced by race but to our knowledge relationships between cancer detection and percent free PSA have not been s tudied. Materials and Methods: A total of 222 black and 298 white consecutive and e valuable men with total PSA 2.5 to 9.9 ng./ml. underwent prostate biopsy fo r suspected cancer at a Veterans Affairs Medical Center. Clinical measureme nts included digital rectal examination, total and free serum PSA, prostate volume, PSA density and Gleason score of malignant biopsy specimens. Results: Median percent free PSA was 14.1 (range 3.6 to 49.2) in 201 men wi th prostate cancer and 21.9 (range 5.7 to 83.3) in 319 without detectable c ancer (p <0.0001). Significant racial;differences in demographic characteri stics and clinical measurements were limited to total PSA, which was higher in black men (p = 0.03). Cancer was detected in 156 black (47%) and 206 wh ite (33%) men (p = 0.001). Areas under receiver operating characteristics c urves for percent free PSA and total PSA were 0.66 and 0.58, respectively, for black men (p = 0.15), and 0.76 and 0.58, respectively, for white men (p <0.00001). Percent free PSA was 35.2 in black men and 29.2 in white men, a nd specificity was 9.1% and 28.7%, :respectively, when sensitivity for perc ent free PSA was set at 95%. Of 156 black and 206 white men with percent fr ee PSA less than 25, 83 (53%) and 85 (41%), respectively, had detectable ca ncer (p = 0.03). Of 66 black and 92 white men with percent free PSA 25 or g reater 21 (32%) and 12 (13%), respectively, had detectable cancer (p = 0.00 5). Conclusions: Our study demonstrates racial differences in relationships bet ween percent free PSA and cancer detection in men with suspected prostatic carcinoma and total PSA 2.5 to 9.9 ng./ml. Clinical application of the comm only used percent free PSA cutoff of less than 25 to determine the advisabi lity of prostate biopsy may lead to under diagnosis of early stage prostate cancer in black men, who are at greater risk of morbidity and mortality fr om disease than white men.