Premium
Significance of free prostate‐specific antigen and gamma‐seminoprotein in the screening of prostate cancer
Author(s) -
Higashihara Eiji,
Nutahara Kikuo,
Kojima Miho,
Okegawa Takatsugu,
Miura Ichiro,
Miyata Akiomi,
Kato Moriaki,
Sugisaki Hajime,
Tomaru Takeshi
Publication year - 1996
Publication title -
the prostate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.295
H-Index - 123
eISSN - 1097-0045
pISSN - 0270-4137
DOI - 10.1002/(sici)1097-0045(1996)7+<40::aid-pros6>3.0.co;2-n
Subject(s) - medicine , prostate specific antigen , prostate cancer , urology , rectal examination , biopsy , prostate , cancer , prospective cohort study , nuclear medicine
BACKGROUND Since free prostate‐specific antigen (PSA) and gamma‐seminoprotein (gamma‐SM) recognize similar epitope(s) of PSA, the significance of serum‐free PSA and gamma‐SM in the early detection of prostate cancer was compared. METHODS A prospective clinical trial was conducted on 701 male volunteers, age 50 years or older. Free PSA (Tandem‐R free PSA, Hybritech) and gamma‐SM (gamma‐SM, Chugai) levels were determined, and biopsies were performed if the PSA (Tandem‐R, Hybritech) level was >4 ng/ml, or if digital rectal examination (DRE) was suspicious. RESULTS One hundred and eighty‐seven men (27%) had either a PSA level >4 ng/ml or a suspicious DRE. Of 116 biopsies performed, cancer was detected in 13 (1.9%, 13/701). Receiver‐operating characteristic analysis of free PSA to PSA ratio (free PSA ratio, %) and gamma‐SM to PSA ratio (gamma‐SM ratio), to differentiate normal biopsy findings from cancer, showed that the optimal values were 12% and 0.38, respectively. Positive predictive value for cancer was 24% (12 cancers/50 biopsies) for PSA alone, 42% (8/19) for the combination of PSA and DRE, 45.5% (10/22) for the combination of PSA and gamma‐SM ratio, and 50% (10/20) for the combination of PSA and free PSA ratio. Regression analysis showed that gamma‐SM highly correlated with free PSA, but that the analytical detection limit of gamma‐SM was 1 ng/ml, significantly higher than that of free PSA. CONCLUSIONS Free PSA determination might effectively eliminate unnecessary biopsies in subjects with PSA >4 ng/ml, and gamma‐SM might provide a complementary index to free PSA, but its validity should be further studied in other settings, such as after radical prostatectomy or during endocrine treatment. © 1996 Wiley‐Liss, Inc.