Immunomagnetic quantification of circulating tumoral cells in patients with prostate cancer: clinical and pathological correlation.

OBJECTIVES: To detect and enumerate circulating prostatic tumor cells (CTC) in the peripheral blood of patients with prostate cancer (PC) and study the relationship between CTCs and clinical-pathological parameters.

METHODS: Prospective three-arm study: 26 patients (p) with localised PC (LPC); 24 P with metastatic PC (MPC) and 30 healthy volunteer controls. A single 7.5 ml sample of peripheral blood was retrieved; CTCs were isolated using an immunomagnetic method based on the CellSearch system (Veridex). CTCs were identified as nucleated cells negative for CD45 (leukocytes) and positive for cytokeratins. (8, 18 y 19) The relationship between CTC numbers and PSA levels, Gleason score and TNM classification was studied.

RESULTS: Only 10% of the healthy controls had 1 CTC/7.5 mL, none of the patients with localised PC had more than 3 CTCs (88% < or = 2 CTCs), and patients with MPC had significantly higher CTC levels [m: 29 (1-178)] compared with the other two groups (P: 0.000). A positive correlation was demonstrated between the CTC count and PSA levels, tumor size, and presence or absence of enlarged lymph nodes. Gleason score was the only parameter that did not show any correlation with CTC levels, and although the number of CTCs was higher in patients with visceral metastases [m: 297 (0-416)] compared with bone metastases patients [m: 68 (9.5-168)] , these differences were not significant.

CONCLUSIONS: Immunomagnetic analysis permits CTCs to be enumerated in peripheral blood and could be a possible way to correctly stage and make a reasonable prognosis of metastatic disease.