Multiplexed fluorescence in situ hybridization–based detection of circulating tumor cells: A novel liquid‐based technology to facilitate accurate and early identification of non–small cell lung cancer patients

Abstract

Lung cancer has the highest mortality and morbidity rate among all malignancies. Because almost all patients are asymptomatic in the early stages of cancer development, the majority of patients are diagnosed with advanced disease. 1 Unfortunately, most of these patients cannot be cured with current therapies. The early detection of lung cancer can provide a window of opportunity to improve care and provide effective treatment to patients at a time when they may be cured. In the United States, the only recommended screening test for lung cancer is low-dose computed tomography (LDCT). 2 LDCT has shown a mild but significant reduction in lung cancer-related deaths and all-cause mortality 3 ; however, it yields a high false-positive discovery rate that exposes patients with nonmalignant lung nodules to unnecessary biopsy-related risks. Therefore, a minimally invasive, easily repeatable, accurate method of lung cancer detection is needed to identify the cohort of at-risk patients who develop disease. Such a method may also be effective in monitoring disease progression or response to therapy.Circulating tumor cell (CTC) technology has emerged and expanded exponentially in the field of liquid biopsy in recent decades. CTCs are rare tumor cells found in the peripheral blood of patients with cancer and can be reliably detected by multiple different CTC platforms. CTCs have been shown to contain a similar genomic landscape to the primary tumors from which they have arisen, 4-7 thus providing valuable insight into the diagnosis and further characterization of primary and metastatic tumors. The critical challenge for these technologies is accurate identification and isolation of extremely rare CTCs from blood (ie, on the order of 10 −9 of all blood cells). A majority of CTC isolation/enrichment techniques employ immunomagnetic capture of epithelial cell adhesion molecule (EpCAM)-positive cells to identify CTCs 8 ; however, these relatively well-established techniques are limited by dependence on EpCAM antibody efficiency and heterogeneity in CTC EpCAM expression. Thus, researchers have also developed alternative enrichment methods based on biophysical properties of CTC, such as size-based filtration and density-based gradient centrifugation. 8 These CTC technologies yield liquid specimens containing tumor cells that can provide diagnostic, prognostic, and predictive information for oncologic patients, and can serve as a valuable extension of diagnostic cytopathology.In this issue of Cancer Cytopathology, Katz et al 9 demonstrate successful detection of cytogenetic changes in peripheral blood mononuclear cells from patients with early stage non-small cell lung carcinoma (NSCLC). The authors modified their previous 2-color FISH detection assay 10 and developed a 4-color FISH-based assay to identify cytogenetic changes and quantify circulating tumor cells (CTCs) from the peripheral blood of patients who are at risk for developing NSCLC. The technique they developed shares similarities with the

Diagnosis of Non-Small Cell Lung Cancer via Liquid Biopsy Highlighting a Fluorescence-in-situ-Hybridization Circulating Tumor Cell Approach

“…CTCs were identified as a complete cell with a nucleus larger than a lymphocyte nucleus that contained polysomy of at least 2 of 4 FISH probes per nucleus. Strikingly, the accuracy of this method to detect early-stage LC was significantly higher than other published EpCAM based technologies, most likely due to the high sensitivity of the 4-color probe cocktail that is used to detect cytogenetically abnormal circulating cells and is not dependent on EpCAM expression [24,71,95].…”