4. Discussion
Increasing evidence suggests that characterization of CTCs
from cancer patients may provide important information
regarding early detection, prognosis, treatment and relapse
as well as improved mechanistic insight with respect to tumor
invasion and metastasis. However, so far, it has been difficult
to establish CTCs as a biomarker for routine clinical use. There
are several reasons for this. In particular, most of the existing
procedures are based on identification of malignant cells by
either cytological features or by antigen detection using
immunofluorescence or immunochemistry. These methods
require highly qualified cytologists and complex quality procedures.
The arrival of the FDA-approved CellSearch analyzer
method has permitted reproductive detection of CTCs based
on automatic numeration of cells with an epithelial