26P - Characteristics of circulating tumor cells (CTCs) in patients with lung cancer

Date 15 April 2016
Event European Lung Cancer Conference 2016 (ELCC) 2016
Session Poster lunch
Topics Lung and other Thoracic Tumours
Translational Research
Presenter Tatjana Vlajnic
Citation Journal of Thoracic Oncology (2016) 11 (supplement 4): S57-S166. S1556-0864(16)X0004-4
Authors T. Vlajnic1, L. Brady2, O. Casey2, K. Gately3, M.P. Barr3, S. Cuffe3, L. Bubendorf1, S. Finn2
  • 1Institute Of Pathology, Universitätsspital Basel, 4031 - Basel/CH
  • 2Department Of Histopathology, St James's Hospital, Dublin/IE
  • 3Thoracic Oncology, St James's Hospital, Dublin/IE

Abstract

Background

Circulating tumor cells (CTCs) are rare cells that shed from the primary tumor or from metastases and can be detected in the peripheral blood. Analysis of CTCs comprises their count and phenotypical and molecular characterization. CTC analysis, also referred to as real-time “liquid biopsy”, can be used as a tool in personalized cancer therapy. Furthermore, CTCs are suitable to explore tumor biology and mechanisms of metastatic spread. Different methods have been developed for CTC isolation. The aim of this study was to determine the utility of a size-based filtration technique in a subset of patients with lung cancer.

Methods

Peripheral blood from 38 patients with lung cancer of different histological subtypes at different stages was processed using a size-based filtration device. The filters were stained with May-Grünwald Giemsa and screened to identify CTCs. Morphology of CTCs was compared to histological biopsies of the primary tumors. Additionally, immunohistochemistry (IHC) was performed to confirm and characterize putative CTCs.

Results

CTCs were identified in 4 of 12 patients with metastatic and 2 of 26 patients with non-metastatic cancer. CTCs were present more often as clusters than single cells. Surprisingly, CTCs did not show specific morphological features of differentiation. CTCs showed subtle cytological atypia and had a different morphology compared to tumor cells from cultured cell lines spiked into healthy donor blood. Additionally, large cells with high nuclear/cytoplasmic ratio were present in all samples. These were negative for cytokeratin and partly positive for ERG, corresponding to megakaryocytes and their precursors.

Conclusions

Identification of CTCs based on morphology alone is not reliable due to minimal cytological atypia and missing morphological features of differentiation. Large cells with cytological atypia, which represent megakaryocytes and their precursors, might be mistaken for CTCs without additional analysis. The impact of CTCs in patients with non-metastatic lung cancer needs to be examined in prospective studies. Molecular characterization of CTCs may contribute to understanding mechanisms involved in tumor progression and metastasis.

Clinical trial identification

no number

Legal entity responsible for the study

Stephen Finn

Funding

Stephen Finn

Disclosure

All authors have declared no conflicts of interest.