Clinical significance of Ki67 and circulating tumor cells with an epithelial-mesenchymal transition phenotype in non-small cell lung cancer.

Circulating tumor cells (CTCs) are a heterogeneous population of tumor cells with distinct clinical and biological properties. The aim of the present study was to evaluate the relationship between CTCs with the epithelial-mesenchymal transition phenotype (CTC EMT) and the proliferative marker Ki67, and their prognostic value in non-small cell lung cancer (NSCLC). CTCs were isolated from the peripheral blood of 84 NSCLC patients using the CanPatrol CTC enrichment method, and the expression of Ki67 in tumor tissues were detected by immunohistochemistry. Almost two-thirds (61/84) of the patients were positive for CTC EMT, and 55 (65.4%) patients had high in-situ expression of Ki67 (≥ 14%) in the tumor tissues. CTC EMT was not significantly associated with tumor size and differentiation, age, gender and histological type, but correlated with lymphatic metastasis, tumor stage and Ki67 overexpression. Furthermore, the CTC EMT+ NSCLC patients had a significantly lower recurrence-free survival (RFS) and overall survival (OS) compared to the negative patients. Similarly, Ki67 levels ≥ 14% were associated with a significantly lower RFS and OS. In conclusion, CTC EMT is significantly related to Ki67 expression, and is a risk factor of NSCLC.