Use of human glandular kallikrein 2 for the detection of prostate cancer: preliminary analysis.
OBJECTIVE
Human glandular kallikrein 2 (hK2) and prostate-specific antigen (PSA) are members of a multigene family of serine proteases that share approximately 80% sequence homology. Both are expressed in the prostate epithelium, are under androgen regulation, are present in serum and seminal fluid, and can form complexes with endogenous protease inhibitors (eg, alpha2-macroglobulin and alpha1-antichymotrypsin). Differences in immunohistochemistry and substrate specificity suggest hK2 may provide unique information for early detection and characterization of prostate cancer.


METHODS
Nine hundred thirty-seven archived serum samples from men treated at two academic institutions were studied. All men underwent biopsy, had a histologically confirmed diagnosis of cancer or noncancer, and a total PSA level greater than 2 ng/mL. Samples were tested in Hybritech's Tandem-R PSA and Tandem-R free PSA (fPSA) assays and a research prototype assay for total hK2 (thK2).


RESULTS
The thK2/fPSA ratio provided additional specificity for cancer detection over PSA and the percentage of fPSA (%fPSA). A model for cancer detection using %fPSA and the thK2/fPSA ratio when PSA is 2 to 4 ng/mL is proposed that would identify as many as 40% of the cancers and would require biopsy in only 16.5% of the men in this PSA range.


CONCLUSIONS
In this study, %fPSA and thK2/fPSA provided unique information for prostate cancer detection and increased the specificity of cancer detection.
Partin
A W
AW
Department of Urology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
Catalona
W J
WJ
Finlay
J A
JA
Darte
C
C
Tindall
D J
DJ
Young
C Y
CY
Klee
G G
GG
Chan
D W
DW
Rittenhouse
H G
HG
Wolfert
R L
RL
Woodrum
D L
DL
D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis*; D020840:Tissue Kallikreins / Q000097:blood*
D020840:Tissue Kallikreins; D017430:Prostate-Specific Antigen