Abstract 629: Label-free isolation of circulating tumor cells for cytomorphological analysis

INTRODUCTION: The isolation of circulating tumor cells (CTCs) from the bloodstream is a promising tool for improving cancer prognosis, targeted therapies, and to understand the biology of metastatic processes. CTC analysis could benefit from conventional cytology staining procedures and cytopathologist expertise in classifying malignant cells from body fluids, to monitor CTC levels in patients in a low-cost system. However, CTCs are very rare with usually only 1-10 CTCs per mL of blood, which limited their use by cytopathologists in the past. Many current approaches for CTC isolation lead to high backgrounds of non-malignant cells (low purity) and/or capture over large areas, which are difficult to analyze microscopically. METHODS: Vortex is a label-free approach for rare malignant cell enrichment from bodily fluids. This technology requires no prior sample preparation, is cost effective and able to deliver viable and pure cells in a small volume. 21 blood samples were processed through our Vortex device. Larger CTCs are trapped within an array of micro-scale fluid vortices that form in simple rectangular reservoirs, while smaller erythrocytes and leukocytes pass through. The tumor cells are released into a small volume of buffer (< 500uL) and collected directly on a chamber slide for fixation and cytological staining using cytopathology standard operating procedures. After Papanicolaou staining, the slides are examined by cytopathologists. RESULTS: Our CTC collection method was optimized to reduce the loss of rare atypical cells during the cytology procedure (>70% cell recovery), improve the cytological staining quality (defined as good by cytopathologists), with an overall fast workflow (