Detection of prostate cancer with a blood-based assay for early prostate cancer antigen.
Prostate-specific antigen lacks specificity for prostate cancer, so the identification and characterization of a unique blood-based marker for the disease would provide for a more accurate diagnosis, reducing both unnecessary biopsies and patient uncertainty. We previously identified a novel biomarker for prostate cancer, early prostate cancer antigen (EPCA). EPCA antibodies positively stained the negative biopsies of men who, as much as 5 years later, were diagnosed with prostate cancer. The goal of this study was to determine whether EPCA antibodies could be used in a clinically applicable plasma-based immunoassay to specifically detect prostate cancer. Using an EPCA-based ELISA, the protein was measured in the plasma of 46 individuals, including prostate cancer patients, healthy individuals, other cancer patients, spinal cord injury victims, and patients with prostatitis. With a predetermined cutoff value of 1.7 absorbance at 450 nm, only the prostate cancer population, as a whole, expressed plasma-EPCA levels above the cutoff. Statistical analysis showed a significant difference in EPCA levels between the prostate cancer population and each of the other groups, specifically the healthy donors (P < 0.0001), bladder cancer patients (P = 0.03), and spinal cord injury patients (P = 0.001). Sensitivity of the EPCA assay for prostate cancer patients was 92% whereas the overall specificity was 94%. Specificity for the healthy donors was 100%. Although larger trials are required, this initial study shows the potential of EPCA to serve as a highly specific blood-based marker for prostate cancer. EPCA, when coupled with prostate-specific antigen, may help reduce the number of both unnecessary biopsies and undetected prostate tumors.
Paul
Barbara
B
Department of Urology, University of Pittsburgh and the University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, USA.
Dhir
Rajiv
R
Landsittel
Douglas
D
Hitchens
Moira R
MR
Getzenberg
Robert H
RH
D000328:Adult; D000368:Aged; D000912:Antibodies, Neoplasm / Q000097:blood / Q000276:immunology; D000951:Antigens, Neoplasm / Q000097:blood* / Q000276:immunology; D014408:Biomarkers, Tumor / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000097:blood* / Q000276:immunology; D012680:Sensitivity and Specificity
D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor