Significance of free to total PSA ratio in men with slightly elevated serum PSA levels: a cooperative study.
BACKGROUND
The ratio of free PSA in total PSA (f/t) has been reported to improve the diagnostic accuracy of prostate cancer in the group with slightly elevated serum PSA values. In Japanese cases, the clinical significance of f/t is still controversial.


METHODS
The diagnostic significance of f/t in serum for prostate cancer was evaluated in a cooperative study. A total of 77 cases with prostate cancer and 224 with non-prostate cancer showing less than 20 ng/ml of total PSA were evaluated.


RESULTS
Serum total and free PSA values were not affected by storage at 25 degrees C for 2 days. The determination of f/t was useful in the cases with a serum total PSA of 5.1-10 ng/ml; the specificity was 60% with a sensitivity of 90% at an f/t of 0.148. The positive predictive value for diagnosis of prostate cancer also increased to 54% from 34% of that in total PSA alone. In the range of 4.1-10 ng/ml, the cut-off value of f/t was 0.155 for obtaining relatively high specificity; sensitivity was 85% and specificity was 56.5%.


CONCLUSIONS
Thus, the determination of f/t was considered to be an effective tool for discriminating the non-prostate cancer cases from those of prostate cancer.
Kuriyama
M
M
Department of Urology, Gifu University School of Medicine, Japan. mkuriyam-gif@umin.u-tokyo.ac.jp
Kawada
Y
Y
Arai
Y
Y
Maeda
H
H
Egawa
S
S
Koshiba
K
K
Imai
K
K
Yamanaka
H
H
D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D012680:Sensitivity and Specificity
D017430:Prostate-Specific Antigen