PURPOSE - To characterize the diagnostic properties of serial percent-free prostate-specific antigen (PSA) in relation to PSA in a multi-ethnic, multi-racial cohort of healthy men.
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MATERIALS AND METHODS - 6,982 percent-free PSA and PSA measures were obtained from participants in a 12 year+ Texas screening study comprising 1625 men who never underwent biopsy, 497 who underwent one or more biopsies negative for prostate cancer, and 61 diagnosed with prostate cancer.
Area underneath the receiver-operating-characteristic-curve (AUC) for percent-free PSA, and the proportion of patients with fluctuating values across multiple visits were determined according to two thresholds (under 15% versus 25%) were evaluated. The proportion of cancer cases where percent-free PSA indicated a positive test before PSA > 4 ng/mL did and the number of negative biopsies that would have been spared by percent-free PSA testing negative were computed.
RESULTS - Percent-free PSA fluctuated around its threshold of < 25% (< 15%) in 38.3% (78.1%), 42.2% (20.9%), and 11.4% (25.7%) of patients never biopsied, with negative and positive biopsies, respectively. At the same thresholds, percent-free PSA tested positive earlier than PSA in 71.4% (34.2%) of cancer cases, and among men with multiple negative biopsies and a PSA > 4 ng/mL, percent-free PSA would have tested negative in 31.6% (65.8%) instances.
CONCLUSIONS - Percent-free PSA should accompany PSA testing in order to potentially spare unnecessary biopsies or detect cancer earlier. When near the threshold, both tests should be repeated due to commonly observed fluctuation.
The Journal of urology. 2016 Mar 12 [Epub ahead of print]
Donna Pauler Ankerst, Jonathan Gelfond, Martin Goros, Jesus Herrera, Andreas Strobl, Ian M Thompson, Javier Hernandez, Robin J Leach
Department of Epidemiology and Biostatistics; Urology University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA; Mathematics, Technische Universitaet Muenchen, Munich, Germany. Department of Epidemiology and Biostatistics., Department of Epidemiology and Biostatistics., Urology University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA., Mathematics, Technische Universitaet Muenchen, Munich, Germany., Urology University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA., Urology University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA., Urology University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.