Purpose: To determine whether the presence of prostate-derived cells in the peripheral blood circulation is a marker of prostate cancer and to define the clinical impact of the test.
Materials and methods: We tested the peripheral blood of 99 patients with prostate adenocarcinoma (PAC), 79 of them undergoing radical prostatectomy, and 92 controls (31 healthy volunteers, 50 patients with adenoma and 11 with prostatitis) using a highly controlled procedure including reverse-transcriptase polymerase chain reaction (RT-PCR) targeted to prostate-specific antigen (PSA) mRNA. Patients were followed for 26 +/- 12 (range: 4 to 49) months. Forty tumor tissues were analyzed by immunohistochemistry for expression of p53 and E-cadherin antigens.
Results: Thirty three (33%) patients with PAC and 2 (2%) controls scored positive (p <0.0001) for the test. Detection of circulating prostatic cells was associated with development of metastases (p <0. 001), with relapse (p <0.001) and with a serum PSA level at diagnosis higher than 15 ng./ml. (p = 0.009). The rate of development of metastases according to time was significantly higher in patients who scored positive for the test (p <0.04). In a multivariate analysis, only the RT-PCR test was an independent risk factor associated with relapse (RR: 6.7). Finally, E-cadherin expression was significantly lower in the tumor tissues of positive patients as compared with those who scored negative for the test (p <0.01).
Conclusions: This RT-PCR procedure, performed at diagnosis and with appropriate controls, is a clinically useful assay in evaluating the risk of tumor recurrence after radical prostatectomy in patients with PAC.