Table 3.

Comparison of the Methods for CTC Analysis and Characterization

Analytical Methods	Advantages	Disadvantages
Immunocytochemistry	Allow CTC morphological analysis; labeling of specific ligands; quantification; and identification	Time-consuming; sometimes subjective evaluation due to expression variation
qRT-PCR	Able to detect specific biomarkers; high sensitivity	Possible false positive results due to WBC contamination
EPISPOT	Ability to detect viable CTCs; to identify specific secreted proteins	Time-consuming; proteins must be actively secreted or released by CTCs
Invasion assay	Examines the ability of CTCs to digest cell adhesion matrix	Time-consuming