The role of circulating tumor cells in evaluation of prognosis and treatment response in advanced non-small-cell lung cancer.

PURPOSE: Non-small-cell lung cancer (NSCLC) lacks validated biomarkers to predict the prognosis and treatment response. This study investigated whether circulating tumor cells (CTCs) detectable could reminder high risk of distant metastasis, provide prognostic information, and early indicate the response to the conventional therapy in patients with advanced NSCLC. PATIENTS AND METHODS: In this single-center prospective study, blood samples for CTC analysis were obtained from 59 patients with previously untreated, stage III or IV NSCLC both before and after administration of two cycles of chemotherapy. CTCs took in peripheral blood were measured by Cell Search detect technique. RESULTS: Carcino-embryonic antigen and count of metastatic sites were positively related to CTC count analyzed by multiple linear regression (P < 0.05). The median overall survival was 11.2 months (95% CI: 10.37-12.03 months) for the baseline CTC ≥ 2 group compared with 8.3 months (95% CI: 7.72-8.88 months) for the CTC < 2 group (log-rank test P < 0.05). Similarly, patients with CTC ≥ 2 at baseline had a significantly shorter median PFS (4.3 months, 95% CI: 3.7-4.9 months) compared with patients with CTC < 2 (6.2 months, 95% CI: 5.59-6.82 months) (log-rank test P < 0.05). For the disease control (stable disease, partial response, or complete response), group CTC value before treatment did not present difference with that after therapy compared by pared-samples T test (t = 1.455, P = 0.154), similar to the result of progressed group (progressive disease) (t = -0.987, P = 0.335). The CTC value of progressed group was higher than that of disease control group either at baseline or post chemotherapy. CONCLUSION: These data provide an evidence of positive correlation between CTC counts with CEA, as well as count of metastatic sites. Meanwhile, CTCs could be an effective predictor of distant metastasis and poor prognosis. In this study, CTCs are poorly related to treatment response. Whether CTCs could be a predictor of curative effect in advanced NSCLC should be validated by more researches in the future.