Usefulness of alpha1-antichymotrypsin-PSA complex for predicting bone metastases of prostate cancer.
OBJECTIVE
To determine the usefulness of alpha1-antichymotrypsin-prostate-specific antigen (PSA) complex (PSA-ACT)-based parameters in predicting bone metastasis in patients with prostate cancer.


METHODS
PSA-ACT, total PSA, free PSA, their volume-adjusted values, and alkaline phosphatase were evaluated in 220 consecutive patients with newly diagnosed prostate cancer.


RESULTS
Bone metastases were detected by bone scan in 27 (12.3%) of the 220 patients. The serum levels of PSA-ACT, total PSA, free PSA, PSA density, PSA adjusted for transition zone volume, PSA-ACT density, PSA-ACT adjusted for transition zone volume, alkaline phosphatase, PSA-ACT/PSA ratio, and Gleason score in patients with bone metastases were each significantly greater than in those without bone metastases. On receiver operating characteristic analyses, PSA-ACT had the greatest area under the curve (0.88), but the receiver operating characteristic curve demonstrated that the sensitivity and specificity of PSA-ACT were marginally better than those of total PSA at only a few selected cutoff points. At a sensitivity of 93% (2 patients with bone metastasis missed), unnecessary bone scans would have been avoided in 107 and 102 patients using a PSA-ACT cutoff value of 10 ng/mL and total PSA cutoff value of 11.5 ng/mL, respectively. Multivariate logistic regression analysis demonstrated that PSA-ACT and Gleason score were significant independent predictors of bone metastasis.


CONCLUSIONS
PSA-ACT is as useful as total PSA for identifying patients with a low probability of having bone metastasis. PSA-ACT could replace PSA for predicting negative bone scans in a clinical setting in which PSA-ACT is used for monitoring and screening patients for prostate cancer.
Kikuchi
Eiji
E
Department of Urology, Keio University School of Medicine, Tokyo, Japan. eiji-k@kb3.so-net.ne.jp
Nakashima
Jun
J
Ishibashi
Midori
M
Ohigashi
Takashi
T
Oya
Mototsugu
M
Nakagawa
Ken
K
Miyajima
Akira
A
Murai
Masaru
M
D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000556:secondary*; D006801:Humans; D008297:Male; D008875:Middle Aged; D046912:Multiprotein Complexes / Q000097:blood; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology*; D000514:alpha 1-Antichymotrypsin / Q000097:blood*
D046912:Multiprotein Complexes; D000514:alpha 1-Antichymotrypsin; D017430:Prostate-Specific Antigen