Morphological Characteristics of Malignancy in Circulating Tumor Cells (CTCs): A New Approach to Liquid Biopsies Utilizing Affordable Standard Cytology Techniques and the FDA Cleared Parsortix® System

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Abstract Introduction/Objective The process of metastasis is responsible for most cancer deaths. Identification of tumor cells circulating in blood (CTCs) has the potential to offer important information to patients and clinicians regarding disease status, longitudinal monitoring, remission status and assessment of patient prognosis, among others. However, currently CTC tests in the market are expensive and are not covered by medical insurance, making them unaffordable for most cancer patients. Legacy CTC technologies also require the use of expensive immunofluorescence microscopes and reagents, and are not easily implemented in standard clinical laboratory settings, thus preventing their use as standard of care. Onc-ADaPT™ Clinical Laboratories have explored a method to identify CTCs using the FDA cleared Parsortix® System (ANGLE plc, Guildford, UK) followed by standard cytology processing, staining and analysis, significantly reducing the cost of operations and increasing the likelihood of affordability to patients everywhere. Methods/Case Report The basic features of malignancy were listed by a Senior Cytologist (CT) and reviewed by another CT. Cancer cell lines were spiked into normal donor blood collected in Streck tubes. Non-spiked healthy volunteer blood was used to establish the background. The samples were then processed through the Parsortix® system producing 200µL suspension of separated cells. The harvest was then processed using Cytospin, stained with standard Pap Stain and reviewed with bright field microscopy by qualified CTs. Results (if a Case Study enter NA) Spiked tumor cells were identified and correctly categorized by the Cytologists. Non-spiked normal donor samples were negative for malignancy. Cells of interest were identified in the non-spiked HNV samples and classified as non-malignant (NOS). Using the training set, CTs later analyzed the available patient sample. The positive cancer patient sample showed cells with obvious characteristics of malignancy. Conclusion The basic characteristics of malignancy used for analysis of standard cytology specimens are adequate to identify CTCs using the established background to eliminate the NOS cells. CTC testing can be performed using the combination of Parsortix® System, standard cytology staining and analysis by qualified Cytologists.