Detection of circulating tumor cells and its correlation with clinical outcome in non-small cell lung cancer.

e22020 Background: The presence of circulating tumor cells (CTCs) is a necessary process for cancer progression. In fact, its detection has surged as a potential biomarker for clinical response in treatment of patients with non-small cell lung cancer (NSCLC). This study analyzed level of CTCs and clinical outcome, as well as expression of genes related to drug resistance. Methods: Consecutive patients of a single institution with stage I-IV NSCLC were included. Isolation, counting and characterization of CTCs were made by ISET (Isolation by Size of Epithelial Tumors; RareCell Diagnostics, Paris, France). Levels of CTCs in blood samples were analyzed before systemic treatment and every two months thereafter. Serum levels of CTCs were correlated with DFS. Expression of ERCC1 was correlated with response to cisplatin-based treatment. Results: 45 patients were included, 2.2% stage I (1 pt), 2.2% stage II (1 pt), 11.1% stage III (5 pts and 75.6% stage IV (34 pts). There were 24 men (53.3%) and 21 women (46.7%) and the median age was 65 years (34-81 years). There was no significant correlation between CTCs´ levels and clinical outcome. However, we observed a non-significant better survival at first follow-up for those found to have less than 2 CTCs/mL (mean = 12.6 months) compared to those with 2 or more CTCs/mL (mean = 5.8 months; p= 0.06). Four patients expressed ERCC1 in their CTCs and three of them showed disease progression, sugesting that this protein has potential to be used as a biomarker. Conclusions: Serum levels of 2 or more CTCs/mL could be a predictor of poor outcome in patients with NSCLC, as was seen in previous studies. The correlation between CTCs expression of ERCC1 and disease progression observed in our analysis needs to be explored in other prospective studies.