Clinical significance of circulating tumor cells in patients with small-cell lung cancer

Background: This study investigated the correlation of the presence of circulating tumor cells (CTCs) with clinical characteristics, and the predictive value of CTCs for progression-free survival (PFS) in patients with small-cell lung cancer (SCLC). Methods: Samples were obtained from 42 patients with SCLC before and after the first cycle of chemotherapy. CTCs were quantitated by negative immunomagnetic enrichment and immunocytochemistry using anti-CD45 and anti-pancytokeratin antibodies. Results: CTCs were positive (>= 2) in 76.19% of patients with SCLC and negative in the control group. The presence of CTCs was positively correlated with 6 clinical characteristics. PFS was 6.055 and 10.670 months for patients with >= 2 and <2 CTCs/7.5 mL of blood before chemotherapy; after chemotherapy PFS was 4.862 and 10.535 months, respectively. Conclusions: This study showed that both baseline CTC numbers and the change in CTC numbers after 1 cycle of chemotherapy are significant prognostic factors of PFS for SCLC.