Prognostic significance of circulating tumor cells in non-small cell lung cancer patients undergoing chemotherapy.

The utility of circulating tumor cells (CTCs) as prognostic biomarkers in non-small cell lung cancer (NSCLC) is inconclusive due to the limitations of current CTC detection methods. Using a novel high-efficiency detection method, we determined the ability of CTCs to predict survival and chemotherapeutic responses in NSCLC. In 127 patients with advanced NSCLC, CTCs were counted and analyzed at baseline and during follow-up. Median overall survival (OS) and progression-free survival (PFS) were longer in patients with baseline CTC counts <8 CTCs/3.2 mL (20.0 vs. 10.4 months [P = 0.009] and 7.2 vs. 5.5 months [P < 0.001], respectively). Patients with post-treatment increases in the CTC count had poorer OS and PFS than those without increases (12.0 vs. 13.3 months [P = 0.028] and 5.2 vs. 6.4 months [P = 0.022], respectively). There was no association between the baseline CTC count and chemotherapeutic response (P = 0.734). However, the rate of progressive disease in patients with and without post-treatment increases in the CTC count were 15.6% and 2.4% (P = 0.042), respectively. The baseline CTC count and the change in the CTC count during treatment were both valuable prognostic indicators for NSCLC.