title: 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.
abstract: 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.
authors.affiliation: Tosei General Hospital, Seto, Japan. nakano@tosei.or.jp
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Nakano
authors.forename: Kikuo
authors.initials: K
authors.lastname: Okamura
authors.forename: Shinichi
authors.initials: S
authors.lastname: Takamura
authors.forename: Noriko
authors.initials: N
authors.lastname: Okamoto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Narishima
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yoshino
authors.forename: Ryohei
authors.initials: R
authors.lastname: Hattori
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Ono
authors.forename: Shinichi
authors.initials: S
authors.lastname: Ohshima
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Nagasaka
mesh_terms: 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*
chemical_list: D014408:Biomarkers, Tumor; D000514:alpha 1-Antichymotrypsin; D017430:Prostate-Specific Antigen