Total and Percent Free Prostate-Specific Antigen Levels

Background: Because total prostate-specific antigen (PSA) and, more recently, the percent free PSA are used to screen men for prostate cancer, population-based, ageand racespecific distributions are needed of both PSA tests among American men to estimate the effect of lowering the PSA threshold or widespread introduction of the free PSA test as an additional screening test. Methods: We did PSA assays on serum samples from men of ages 40 years and older (n = 1,320) who participated in the 2001-2002 National Health and Nutrition Examination Survey. Results: About 6.1% (95% confidence interval, 4.7-7.7%), corresponding to an estimated 3.4 million (range, 2.7-4.3 million) men nationwide, ages 40 years and older, had a total PSA of >4.0 ng/mL. Among men ages 50 to 69 years old, the age group for which PSA testing is most prevalent, 5.4% or an estimated 900,000 to 2 million men had a total PSA of >4.0 ng/mL. An equal number had a total PSA between 2.5 and 4.0 ng/mL and a percent free PSA of <25%. Approximately 27% of men in this age group, corresponding to a range of 5.7 to 8.1 million men, had a total PSA <2.5 ng/mL and a percent free PSA of <25%. Conclusion: The effect of lowering the total PSA threshold or introducing another screening test is significant. Provision of the number of U.S. men with certain total PSA and percent free PSA values may help guide prostate cancer public health policy and screening practices. (Cancer Epidemiol Biomarkers Prev 2005;14(9):2178–82)