7080 Background: Circulating tumor cell (CTC) is a surrogate of distant metastasis, and our preliminary study suggested that CTC detected by an EpCAM-based immuno-magnetic separation system (“CellSearch”) was a useful clinical marker in the diagnosis of malignant pleural mesothelioma (MPM) (Tanaka F. et al ASCO 2008). Methods: Patients who presented at our institute to receive pleural biopsy with suspicion of MPM were prospectively enrolled. CTCs in 7.5mL of peripheral blood were quantitatively evaluated with the CellSearch system. Results: Among 136 eligible patients, 104 were finally diagnosed with MPM, and 32 were with non-malignant diseases (NM). CTC was positive (CTC≥1) in 32.7% (37/104) of MPM pts, and in 9.4% (3/32) of NM pts (p=0.011). CTC-count was significantly higher in MPM (range, 0-9) than in NM (range, 0-1; p=0.007). According to a ROC curve analysis, the CTC-test provided a significant diagnostic performance in discrimination between MPM and NM (AUC= 0.623; P=0.036). Among MPM pts, CTC-positivity and CTC-count were significantly increased with tumor progression (p=0.026 and p=0.008, respectively). For all MPM pts, there was no significant difference in overall survival between CTC-positive and negative pts. However, in a planned subset analysis, CTC was a significant factor to predict poor prognosis (median survival time, 8.0 months for CTC-positive pts, and 20.3 months for negative pts; p=0.012) in pts with epithelioid-type MPM in which CTC was exclusively positive; a multivariate analysis confirmed that CTC, along with PS, was an independent prognostic factor (HR=2.38; P=0.006). Conclusions: CTC was a significant diagnostic marker in discrimination between MPM and NM. CTC-positivity was a significant and independent prognostic factor to predict a poor prognosis of epithelioid MPM. [Table: see text]
Aminopeptidase N/CD13 as a potential therapeutic target in malignant pleural mesothelioma