The prognostic impact of circulating tumor cells in patients with small cell lung cancer.

10617 Background: There has been an increasing interest in the circulating tumor cells (CTC) in various solid tumors for predicting clinical outcomes. The aim of this study is to evaluate the relationship between CTC-count and prognosis in patients with small cell lung cancer (SCLC). Methods: A total of 51 patients with newly diagnosed SCLC who had received chemotherapy were prospectively enrolled (27 with limited disease and 24 with extensive disease). Blood samples were drawn at baseline, after chemotherapy, and at the time of relapse. CTCs were isolated using the CellSearch System (Veridex LLC). Results: CTCs at baseline were detected in 40 patients, 78.4% (95% CI, 65.4-87.5), and the median CTC-count was 4 (0-5,648) per 7.5ml. The patients with CTC-count of <9 (favorable group) lived longer than those with CTC-count of >=9 (unfavorable group) when measured at baseline, after treatment, and at the time of relapse; adjusted hazard ratio (95% CI) were 8.9 (2.5-43.1), 4.7 (1.1-19.1), and 8.1 (2.0-47.3), respectively. Patients whose CTC-count remained favorable after chemotherapy showed better survival than those converted from unfavorable to favorable (hazard ratio, 8.1 [1.9-42.0]) or those remained unfavorable after treatment (hazard ratio, 12.3 [2.3-78.3]). Conclusions: CTCs were highly detectable in SCLC and a higher CTC-count was strongly associated with shorter survival from any point of blood draw. Remaining favorable CTC-count or conversion from unfavorable to favorable CTC-count might indicate better prognosis than remaining unfavorable CTC-count after chemotherapy.