Circulating tumor cells (CTCs), detached from the primary tumor or metastases and shed in the patient's bloodstream, represent a relatively easily obtainable sample of the cancer tissue that can indicate the actual state of cancer, and their evaluation can be repeated many times during the course of treatment. As part of liquid biopsy, evaluation of CTCs provides a lot of clinically relevant information, which reflects the actual, real-time conditions of the disease. CTCs can be used in cancer diagnosis or screening, real-time long-term disease monitoring and even therapy guidance. Their analysis can include their number, morphology, and biological features by using immunocytochemistry and all “-omic” technologies. This review describes methods of CTC isolation and potential clinical utilization in lung cancer.

AIM: To investigate the feasibility of separation and cultivation of circulating tumor cells (CTCs) in pancreatic cancer (PaC) using a filtration device. METHODS: In total, 24 PaC patients who were candidates for surgical treatment were enrolled into the study. Peripheral blood samples were collected before an indicated surgery. For each patient, approximately 8 mL of venous blood was drawn from the antecubital veins. A new size-based separation MetaCell^® technology was used for enrichment and cultivation of CTCs in vitro. (Separated CTCs were cultured on a membrane in FBS enriched RPMI media and observed by inverted microscope. The cultured cells were analyzed by means of histochemistry and immunohistochemistry using the specific antibodies to identify the cell origin. RESULTS: CTCs were detected in 16 patients (66.7%) of the 24 evaluable patients. The CTC positivity did not reflect the disease stage, tumor size, or lymph node involvement. The same percentage of CTC positivity was observed in the metastatic and non-metastatic patients (66.7% vs 66.7%). We report a successful isolation of CTCs in PaC patients capturing proliferating cells. The cells were captured by a capillary action driven size-based filtration approach that enabled cells cultures from the viable CTCs to be unaffected by any antibodies or lysing solutions. The captured cancer cells displayed plasticity which enabled some cells to invade the separating membrane. Further, the cancer cells in the “bottom fraction”, may represent a more invasive CTC-fraction. The CTCs were cultured in vitro for further downstream applications. CONCLUSION: The presented size-based filtration method enables culture of CTCs in vitro for possible downstream applications.

Circulating tumor cells (CTCs) are important targets for treatment and critical surrogate markers when evaluating cancer prognosis and therapeutic response. A sensitive methodology for detecting CTCs in gastric cancer (GC) patients is needed. In this study we demonstrate a device for enrichment and cultivation of CTCs. In total, 22 patients with GC, all candidates for surgery, were enrolled in the study. Peripheral blood samples were collected before surgery, and patients were re-evaluated within operation and divided into two groups: resectable and non-resectable GC. A new size-based separation test for enrichment and cultivation of CTCs was used (MetaCell^®). In addition to cytomorphological analysis, gene expression of tumor associated genes (Cytokeratin-18, Cytokeratin-19, Cytokeratin-20, Cytokeratin-7, EPCAM, MUC1, HER2, EGFR) and of leukocyte markers (e.g. CD45, CD68) was tested in enriched CTC fractions. CTCs were detected in 59 % of the patients studied (n = 13/22). CTCs were detected in seven patients of the resection group (7/10, 70 %) and six of the non-resectable group (6/12, 50 %). Enrichment of the viable CTCs allowed subsequent successful cultivation in vitro. The cytomorphological characterization of the CTCs was a prerequisite of random gene expression testing in CTC-positive samples. In CTC-positive samples gene expression of cytokeratin 18 and 19 was elevated in comparison to the whole blood gene expression analysis. CTCs were found to be present in both resectable and non-resectable gastric cancer patients. The size-based separation platform for CTCs may be used for in vitro cultivation, as well as in subsequent molecular analysis if desired. The sensitivity of CTC-detection could be enhanced by the combination of cytomorphological and molecular analysis.