The influence of prostate volume on the ratio of free to total prostate specific antigen in serum of patients with prostate carcinoma and benign prostate hyperplasia.
BACKGROUND
Determining the ratio of free to total prostate specific antigen (f-PSA to t-PSA, calculated as the percentage of f-PSA [f-PSA%]) in serum allow for a clearer distinction between patients with prostate carcinoma (PCa) and patients with benign prostate hyperplasia (BPH) than determining the level of t-PSA alone. To find influencing factors on f-PSA%, the authors investigated prostate volume, TNM classification, and tumor stage.


METHODS
The authors measured f-PSA and t-PSA in 36 men with untreated PCa (tumor classification: T1, 2, 3pNO, MO), 44 patients with BPH, and 54 healthy controls. Prostate volume was determined by transrectal ultrasound.


RESULTS
The median values of t-PSA and f-PSA% were 7.8 micrograms/L and 10.5% in PCa patients, 4.3 micrograms/L and 20.8% in patients with BPH, and 1.4 micrograms/L and 23.6% in the control group. Patients with PCa had a significantly lower proportion of f-PSA than BPH patients and healthy men. There was no correlation of f-PSA% to TNM stage or tumor grade. In PCa patients a significant positive correlation (correlation coefficient [r] = 0.51, P < 0.001) was found between f-PSA% and prostate volume, whereas there was no significant correlation in BPH patients (r = -0.27, P > 0.05). There was a significant difference in f-PSA% between PCa and BPH patients with prostate volumes smaller than 40 cm3 (9.0% vs. 21.6%, P < 0.01) but not between patients in these 2 groups with prostate volumes exceeding 40 cm3 (15.1% vs. 18.2%, P = 0.11).


CONCLUSIONS
Determining the ratio of f-PSA to t-PSA to discriminate between PCa and BPH patients yields significant results only in men with a prostate volume of less than 40 cm3.
Stephan
C
C
Department of Urology, University Hospital Charité, Humboldt University Berlin, Germany.
Lein
M
M
Jung
K
K
Schnorr
D
D
Loening
S A
SA
D000368:Aged; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood* / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology*; D012680:Sensitivity and Specificity
D017430:Prostate-Specific Antigen