Detection and phenotyping of circulating tumor cells in high-risk localized prostate cancer

Background In this study, we aimed to determine the feasibility of identifying CTCs in patients with HRLPC, using a modified isolation procedure using the CellSearch (Veridex) platform, and to assess the expression of stem cell and epithelial-mesenchymal transition (EMT) markers on the CTCs. Patients and Methods Thirty-five patients with HRLPC who had chosen prostatectomy for definitive management were prospectively identified. After obtaining consent, four 30-mL blood draws were performed, 2 before surgery and 2 after surgery. The CTC-containing fraction was Ficoll-purified and transferred to a CellSave (Veridex) tube containing dilution buffer before standard enumeration using the CellSearch system. Loss of E-cadherin expression, a marker of EMT, and CD133, a putative prostate cancer stem cell marker, were characterized using the open channel of the CellSearch platform. CTC fragments were also enumerated. Results Using the modified methodology, CTCs were detectable in 49% of patients before surgery. Although no correlation between CTC count and biochemical recurrence (BR) was observed, the percentages of CD133 and E-cadherin-positive CTC fragments were associated with BR at 1 year. Conclusion Our results suggest that further research into the development of CTCs as prognostic biomarkers in HRLPC is warranted.