Highly specific detection of prostate-specific antigen-positive cells in the blood of patients with prostate cancer or benign prostatic hyperplasia, using a real-time reverse-transcription-polymerase chain reaction method with improved sensitivity.
OBJECTIVE
To assess the presence of circulating prostate-specific antigen (PSA)-expressing cells in patients with prostate cancer or benign prostatic hyperplasia (BPH), and to determine their diagnostic usefulness using a highly sensitive quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) method.


METHODS
Venous blood samples were obtained from 175 patients with prostate cancer (12 metastatic and 163 not metastatic), 49 with BPH, and 50 healthy volunteers. To improve the specificity and sensitivity of the qRT-PCR three innovative features were combined; a primer overlapping two adjacent exons to inhibit nonspecific amplification; a no-end-point first round amplification to increase the sensitivity; and a target-specific primer for the RT phase to increase the specificity.


RESULTS
The sensitivity of the method was 1 cell/mL of blood and the interassay coefficient of variation was 10.5%. None of the healthy subjects tested positively, while 9% of those with prostatic cancer and 14% with BPH had PSA-positive cells in the blood. There was a positive association between a positive test and the National Comprehensive Cancer Network classification in the patients with newly diagnosed prostate cancer (P = 0.022). There were no additional statistically significant associations.


CONCLUSIONS
Our results strongly indicate that although there were no false-positive results and the sensitivity of the method was increased to maximal levels, a low frequency of positive results in patients with prostatic cancer and a high frequency of positive results in those with BPH seems to discourage the use of PSA-positive circulating cells in the search for a clinical diagnosis of prostate cancer.
Dipartimento de Genetica, Biologia e Biochimica, Università di Torino, Torino, Italy.
Giovanna
G
Barbero
Paolo
P
Destefanis
Simone
S
Procida
Giorgia
G
Mandili
Daniela
D
Ulliers
Carlo
C
Ceruti
Cristian
C
Fiori
Milena M
MM
Maule
Dario
D
Fontana
Giuliana
G
Giribaldi
Franco
F
Turrini
D005240:Feasibility Studies; D006801:Humans; D008297:Male; D009360:Neoplastic Cells, Circulating / Q000737:chemistry / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000175:diagnosis*; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000592:standards*; D012680:Sensitivity and Specificity
D017430:Prostate-Specific Antigen