Biological Variation of Serum Prostate Specific Antigen Levels in Men Aged 50 or Older without Prostate Cancer / 대한비뇨기과학회지

ABSTRACT

PURPOSE: To evaluated the effect of the intra-individual variation in the serum prostate specific antigen (PSA) level in men without prostate cancer to decide on the requirement of a prostate biopsy. MATERIALS AND METHODS: Patients, aged between 50 and 80 years, were screened for prostate cancer or lower urinary tract symptoms at least 2 times within 3 months using PSA or free PSA measurements. Patients with an initial PSA level between 2.0 and 10.0ng/ml were included. Those with prostate cancer, urinary tract infection or 5-alpha reductase inhibitor medication were excluded. The coefficient of variation (CV) was evaluated in each PSA range. RESULTS: The analysis included 139 patients, with a mean age 62.1 years. The level of free PSA was measured in 56 patients. The mean interval between the two PSA measurements was 36.6 days. The mean CVs for the total PSA and % free PSA were 21.5 and 22.2%, respectively. 20% of patients show a CV of more than 30%, implying a large variation. In our study, the 95% confidence interval of initial PSA levels between 3.0 and 4.9ng/ml included the PSA cut-off point (4.0ng/ml) in the visit results. CONCLUSIONS: The variation the PSA level was relatively small, but some patients showed a CV greater than 30%. Therefore, the intra-individual PSA variation should become part of interpreting the PSA test results, especially for men with a PSA value near the cut-off point.