Multiplex characterization of circulating tumor cells from ductal carcinoma in situ patients suggests early tumor dissemination.

While ducal carcinoma in situ (DCIS) is considered to be pre-invasive, some patients will develop metastatic disease after a long disease-free interval. The prevailing dogma posits that invasive local recurrence is the source of subsequent metastasis, and thus the goal of DCIS therapy is the prevention of local recurrence. Recently, this paradigm has been called into question by the observation that some women develop metastatic disease in the absence of local recurrence or even following bilateral mastectomies, suggesting early cancer dissemination in some patients. If the presence of circulating tumor cells (CTCs) can be verified on some patients with pure DCIS, then dissemination may be occurring earlier than previously thought, suggesting that these patients might require additional monitoring or treatment. Here, we present a workflow to isolate and characterize CTCs from DCIS patients. Using a high throughput size based inertial focusing microfluidic device, the Labyrinth, we isolated and identified CTCs in 66.6 % (12/18) of DCIS patients with an average of 1.337 CTCs per five mL. Immunofluorescence staining and single cell qPCR of CTCs reveal mesenchymal characteristics of the cells that may contribute to their ability to migrate and metastasize. Preliminary targeted DNA sequencing revealed single nucleotide variations previously found in DCIS samples. Overall, this data supports the hypothesis that cancer dissemination is occurring in a subset of DCIS patients earlier than previously thought. Additionally, the molecular characterization of CTC in DCIS patients may provide important information on their biological characteristics and associated clinical behavior.