Free-to-total prostate specific antigen ratio as a single test for detection of significant stage T1c prostate cancer.
OBJECTIVE
We investigated whether impalpable, invisible (stage T1c) but significant prostate cancer can be detected better by determining the free-to-total prostate specific antigen (PSA) ratio of equivocal PSA serum levels.


METHODS
The specificity of free-to-total PSA ratio using research monoclonal enzyme immunoassays was compared to that of PSA greater than 4.0 ng./ml. in 117 consecutive patients with PSA 3 to 15 ng./ml. (Hybritech Tandem-R assay) due to untreated benign prostatic hypertrophy or prostate cancer. Of the patients 77% underwent adenectomy or radical prostatectomy with thorough pathological evaluation of surgical specimens.


RESULTS
Benign prostatic hypertrophy had a greater median free-to-total PSA ratio than stages T1c and T2 or greater prostate cancer (0.16 versus 0.09 and 0.11 ng./ml., p = 0.0001 and p = 0.0268, respectively). In stage T1c prostate cancer, areas under receiver operating characteristic curves were 0.58 and 0.84 for PSA and free-to-toal PSA ratio, and free-to-total PSA ratio correlated with prostate volume (r = 0.49, p = 0.005) and Gleason score (r = -0.37, p = 0.036). Pathologically, 84% of stage T1c cancers were significant and comparable to stage T2 or greater cancers.


CONCLUSIONS
Free-to-total PSA ratio enhances the efficacy of PSA measurement by improving specificity for detecting impalpable, invisible but significant stage T1c prostate cancer.
Elgamal
A A
AA
Department of Urology, University Hospitals of KU Leuven, Belgium.
Cornillie
F J
FJ
Van Poppel
H P
HP
Van de Voorde
W M
WM
McCabe
R
R
Baert
L V
LV
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis*; D012372:ROC Curve; D012680:Sensitivity and Specificity
D017430:Prostate-Specific Antigen