Circulating Nucleic Acids in Colorectal Cancer: Diagnostic and Prognostic Value

Table 1

The challenges of current semiautomated strategies for CTCs extraction and molecular quantification.

Methods	Challenges	References
The cell search system	Low sensitivity (false negative) due to only EpCAM-positive CTCs consideration or missing CTCs subclusters engaged in EMT, low specificity (false positive), small productivity, and diverse specimen testing for direct recognition and evaluation of intact cells in the epithelial cellular adhesion molecule (EpCAM)-based cell search R system	[24]
Microfluidic-based positive enrichment technologies	Complete separation proficiency by a single or multiple capture antibodies for pathology-specific target cells in small fluid volumes after laminar flow without pretagging	[25–27]
DNA or RNA sequencing	Absence of smaller CTCs or CTC fragments as a result of a false-positive test	[28–30]
Biophysical CTCs extraction	Requirement of spiked-in experiments for validation of different CTC isolation approaches prior to more accurate clinical reliability for removing interference with large leukocytes (e.g., monocytes) and CTCs due to their small size and low frequency of size-based techniques below 10%	[28–30]