Population-based Analysis of Normal Total PSA and Percentage of Free/Total PSA Values: Results From Screening Cohort

ObjectivesTo examine the distribution of total prostate-specific antigen (tPSA) and percentage of free/total PSA (%f/tPSA) values in patients undergoing prostate cancer screening in Canada.MethodsThe data from 4 consecutive annual prostate cancer screening events held in Montreal, Canada were examined with respect to age, tPSA, and %f/tPSA in 3222 men.ResultsWithin the entire cohort, the median PSA level was 1.0 ng/mL and the median %f/tPSA was 26%. Using the interquartile range around the median, the upper bound for tPSA was situated at 1.9 ng/mL and the lower bound for %f/tPSA was at 19%. The 90th percentile for the median tPSA was 3.8, and the 10th percentile for the median %f/tPSA was 14. PSA and %f/tPSA showed a relation with age. The 75th percentile for the median tPSA level in the age category 40-49, 50-59, 60-69, and 70-79 years was 1.1, 1.4, 2.6, and 3.6 ng/mL, respectively. The 25th percentile for the median %f/tPSA level in the age category 40-49, 50-59, 60-69, and 70-79 years was 19, 21, 18 and 19 ng/mL, respectively.ConclusionsOur results can guide clinicians regarding the population-based distribution of serum tPSA and %f/tPSA values. Those values can be used for the purpose of counseling, as well as in the informed consent process before prostate biopsy.