Measurement of prostate specific antigen complexed to alpha1-antichymotrypsin to avoid unnecessary biopsy in patients with serum prostate specific antigen levels 4-20 ng/mL.
OBJECTIVE
To investigate whether measuring prostate specific antigen complexed to alpha1-Antichymotrypsin (PSA-ACT) can increase sensitivity and specificity in detecting prostate cancer.


METHODS
In this prospective study, we measured serum total PSA, PSA-ACT, free PSA, prostate volume and transition zone volume on 210 patients with total PSA level of 4-20 ng/mL. From fitted curves between positive predictive values for prostate cancer and age, prostate volume, transition zone volume, total PSA, PSA-ACT or F/T ratio, each function predicting prostate cancer was determined. Relative probabilities for prostate cancer (RPpca) which were defined by combined functions of age, F/T ratio, prostate volume or transition zone volume, and total PSA or PSA-ACT were calculated. Furthermore, using logistic regression, analysis was performed to determine the probability of prostate cancer. Receiver-operating characteristic analysis was performed to clarify the areas under the curve (AUC) for conventional single parameters, RPpca and logistic regression probability.


RESULTS
F/T ratio showed the largest AUC among conventional parameters. The AUC of RPpca was larger than those of F/T ratio and logistic regression probability. RPpca using the functions of age, transition zone volume, PSA-ACT and F/T ratio showed the largest AUC and highest specificity at sensitivity 95% level, however, specificities at sensitivity 90% and 85% were identical to those of RPpca using the functions of age, prostate volume, total PSA and F/T ratio.


CONCLUSIONS
RPpca using the functions of age, transition zone volume, PSA-ACT and F/T ratio was the best way to detect prostate cancer, however, the usefulness of PSA-ACT appears limited, considering the cost.
Nakano
Yojiro
Y
Tosei General Hospital, Seto, Japan. nakano@tosei.or.jp
Okamura
Kikuo
K
Takamura
Shinichi
S
Okamoto
Noriko
N
Narishima
Masahiro
M
Yoshino
Yasushi
Y
Hattori
Ryohei
R
Ono
Yoshinari
Y
Ohshima
Shinichi
S
Nagasaka
Tetsuro
T
D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D001706:Biopsy; D006801:Humans; D007564:Japan; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology*; D012680:Sensitivity and Specificity; D019564:Unnecessary Procedures; D000514:alpha 1-Antichymotrypsin / Q000097:blood*
D014408:Biomarkers, Tumor; D000514:alpha 1-Antichymotrypsin; D017430:Prostate-Specific Antigen