title: Prostate-specific antigen (PSA) complexed to alpha1-antichymotrypsin improves prostate cancer detection using total PSA in Japanese patients with total PSA levels of 2.0-4.0 ng/mL.
abstract: OBJECTIVE
  To assess the utility of prostate-specific antigen (PSA) complexed to alpha1-antichymotrypsin (PSA-ACT) in prostate cancer screening in Japanese men with a total PSA level of 2.0-4.0 ng/mL, as improving cancer detection in men with these total PSA levels is a challenge for clinical urologists.
  
  
  METHODS
  Total PSA and PSA-ACT were prospectively assessed and prostate biopsy recommended for patients who met either of two thresholds, i.e. a total PSA of > or = 2.0 ng/mL or a PSA-ACT of > or= 1.5 ng/mL. The diagnostic ability of total PSA and PSA-ACT, and free-to-total PSA ratio and prostate volume-adjusted density were evaluated by receiver operating characteristic (ROC) analysis.
  
  
  RESULTS
  Of 1003 men enrolled, 547 met the biopsy criteria and a biopsy was taken in 315 (57.6%) patients. The area under the ROC curve for PSA-ACT (0.679) was significantly greater than that for total PSA (0.601, P = 0.04) and equivalent to that for the free-to-total ratio (0.686, P = 0.911) in 116 men, including 27 with cancer with total PSA levels of 2.0-4.0 ng/mL. PSA-ACT was more specific than the free-to-total ratio at a sensitivity of 95% (36% vs 18%, P < 0.05). The best variable for discriminating between cancer and benign disease in men with PSA levels of 2.0-4.0 ng/mL was PSA-ACT density (area under the curve 0.852) which provided 66% specificity at a sensitivity of 90%.
  
  
  CONCLUSIONS
  PSA-ACT is better than total PSA and equivalent to the free-to-total ratio for detecting prostate cancer in men with PSA levels of 2.0-4.0 ng/mL, and is thus useful for reducing the number of unnecessary biopsies.
authors.affiliation: Department of Urology, Hamamatsu Rosai Hospital, Shogen-cho 25, Hamamatsu, Japan, 430-8525. selecao@remus.dti.ne.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kamoto
authors.forename: Koji
authors.initials: K
authors.lastname: Nishizawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Mitsumori
authors.forename: Keiji
authors.initials: K
authors.lastname: Ogura
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ide
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis*; D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D015842:Serine Proteinase Inhibitors / Q000378:metabolism*; D000514:alpha 1-Antichymotrypsin / Q000378:metabolism*
chemical_list: D015842:Serine Proteinase Inhibitors; D000514:alpha 1-Antichymotrypsin; D017430:Prostate-Specific Antigen