Circulating tumor cells as a prognostic marker in metastatic non-small-cell lung cancer patients receiving chemotherapy.

Abstract

11041 Background: Radiographic response remains the gold standard for assessment of the chemotherapy effect and has been used as a surrogate endpoint in clinical trials. Recently, circulating tumor cells (CTC) have emerged as a novel prognostic marker in many types of cancer; however, their significance has not been fully examined in patients with non-small-cell lung cancer (NSCLC). Methods: We conducted a prospective study to evaluate the clinical significance of CTC in metastatic NSCLC patients treated with chemotherapy. Peripheral blood samples were collected for CTC analysis before chemotherapy, after 1 cycle of chemotherapy, and after 2 cycles of chemotherapy. CTC analysis was performed using CellSearch (Veridex). Results: One hundred and forty-eight patients wereenrolledbetween August 2009 and January 2012, and 121 patients were eligible for the analysis. CTC was positive (CTC ≥1) in 30.6% (37/121) before chemotherapy, in 21.0% (26/118) after 1 cycle of chemotherapy, and in 21.6% (24/111) after 2 cycles of chemotherapy, respectively. CTC counts were higher in patients with N3 lymph node metastases (vs. N0-2, p = 0.0001), M1b status (vs. M1a, p = 0.0081) or ≥2 metastasis sites (vs. 1 metastasis site, p = 0.0342). Although not statistically significant, a positive trend was observed between the radiographic response and the dynamic change of CTC counts (p = 0.0734). In multivariate analysis, including the radiographic response (responder vs. non-responder), baseline CTC was a significant negative predictive factor for PFS (HR = 1.867; p = 0.0080) and OS (HR = 2.753; p = 0.0006). Considering pre- and post-treatment time points (before and after 2 cycles of chemotherapy) together, CTC-positive patients at either time point experienced significantly worse PFS (HR = 1.747; p = 0.0143) and OS (HR = 2.031; p = 0.0123) than those who were CTC negative at both time points. Conclusions: CTC was an independent prognostic factor in patients with metastatic NSCLC who was treated with chemotherapy.