Purpose: Using prostate-specific antigen (PSA) mRNA as a marker for prostatic epithelial cells, we have developed a sensitive technique that involves reverse transcription and polymerase chain reaction (RT-PCR) to detect circulating tumor cells in the peripheral blood of men with prostatic carcinoma (CaP).
Patients and methods: A sensitive RT-PCR assay was used to evaluate the peripheral blood of 135 men with a history of CaP. Fourteen men with benign prostate disease, many of whom had elevated serum PSA levels, were used as a control group.
Results: All patients with benign prostate disease had a negative result in the RT-PCR assay. Of particular interest was a subgroup of 65 patients with clinically localized CaP evaluated before definitive local therapy. Five of these patients had detectable PSA mRNA by RT-PCR, suggesting circulating tumor cells. Within this group, systemic disease was detected by RT-PCR in some men with PSA levels less than 10 ng/mL and clinical stage B disease. Blood from men with hormone-refractory and progressive CaP demonstrated a higher frequency of PSA mRNA detectable by RT-PCR (10 of 20 patients). In contrast, none of seven patients with newly diagnosed metastatic prostate cancer and only one of seven patients with metastatic, hormone-responsive disease had blood that was positive for PSA mRNA by RT-PCR.
Conclusion: Circulating tumor cells can be detected in the blood of a subset of patients with clinically localized CaP and a larger subset of patients with progressive metastatic disease.