POSITIVE PROSTATE-SPECIFIC ANTIGEN CIRCULATING CELLS DETECTED BY REVERSE-TRANSCRIPTASE POLYMERASE-CHAIN-REACTION DOES NOT IMPLY THE PRESENCE OF PROSTATIC MICROMETASTASES

Objectives. Detection of circulating tumor cells may improve the preop erative local staging of prostate cancers. The aim of this study was t o perform enhanced reverse transcriptase-polymerase chain reaction (RT -PCR) of prostate-specific antigen (PSA) mRNA to define the predictive value of PSA-positive circulating cells in a large series of patients . Methods, The study included 46 patients with Stage T1 to T2 prostate cancer, 94 with benign prostatic hyperplasia (BPH), and 51 (including 9 women) with nonprostatic disease. PSA-positive cells from periphera l blood samples were detected by Southern blot analysis of the RT-PCR products, Original oligonucleotide primers were defined to exclusively detect the three PSA mRNA splices. Results, Circulating PSA-positive cells were observed in 8 (8.5%) of 94 patients with BPH, 10 (22%) of 4 6 with Stage T1 to T2 prostate cancer, and 9 (17.6%) of 51 with nonpro static disease. The detection rate of PSA-positive circulating cells w as significantly increased in patients with prostate cancer versus pat ients with BPH (P = 0.03). Among clinically localized prostate cancers with a Gleason score less than 8, a correlation was observed between PSA-positive circulating cells and Stage pT3 cancer (P = 0.038), capsu lar penetration (P = 0.04), and a positive margin (P = 0.038). The spe cificity of the assay for Stage pT3 cancer detection was 84.6%, with a positive predictive value of 60%. Conclusions, Although RT-PCR assay may have a role in preoperative local staging, this study demonstrated the absence of tissue and tumor specificity of PSA-positive circulati ng cells, accounting for the weak positive predictive value of this te chnique. (C) 1997, Elsevier Science Inc. All rights reserved.