Ratio of free to total prostate-specific antigen in patients with prostatic intraepithelial neoplasia

Objective: There are many reports about the effects of prostatic intraepithelial neoplasia (PIN) on serum prostate-specific antigen (PSA) level. The aim of this study was to determine the relationship between PIN and serum free PSA/total PSA (fPSA/tPSA) ratios. Methods: We evaluated 46 patients with PIN, 15 patients with benign prostatic hyperplasia (BPH), and 16 patients with localized prostatic carcinoma (CaP) for the amount of fPSA and tPSA with the chemiluminescent enzyme assay. Results: fPSA values from BPH to high-grade PIN (PIN2 and PIN3) was increased, and then a decrease was observed from high-grade PIN to CaP. fPSA was significantly different between BPH and low-grade PIN and high-grade PIN. There was no significant difference observed between BPH and CaP, tPSA values increased from BPH to CaP, tPSA was significantly different between BPH and high-grade PIN and CaP, fPSA/tPSA ratios decreased from BPH to CaP, This ratio was significantly different between CaP and BPH and low-grade PIN. There was no significant difference between CaP and high-grade PIN. Conclusions: Our results confirm that fPSA/tPSA ratio is better at discriminating between patients with CaP and those with BPH, but not between patients with CaP and those with high-grade PIN. Due to similarities between CaP and high-grade PIN, we think that decreased fPSA/tPSA ratio obtained at the time of intial diagnosis of PIN without concurrent carcinoma could be used as predictive factors to distinguish patients in whom carcinoma will be found on subsequent biopsies from those with PIN not associated with cancer on repeat biopsy.