Table 1.
Summary of advantages and disadvantages of using CTCs, ctDNA and exosomes as biomarkers in cancer
| Advantages | Disadvantages | Reference | |
|---|---|---|---|
| CTCs | • Information can be provided at the protein, DNA and RNA levels | • CTCs are rare (1 cell in 109 blood cells) | 25,28,47,75 |
| • Possibility of carrying out functional assays | • May represent only part of the tumour mass heterogeneity | ||
| • There are new technologies in the development phase to isolate CTCs | • Process to isolate them is challenging | ||
| ctDNA | • Higher ctDNA levels compared with CTC | • Short half-life, <1.5 h | 23,25,46,75 |
| • Levels correlate with disease stage | • Released mainly by cells undergoing necrosis or apoptosis | ||
| • Easy detection | |||
| Exosomes | • Can be released by all cells, including tumour cells | • The release is not exclusive from tumour cells | 25,115,135 |
| • Can carry proteins, DNA, RNA and miRNA | • Possible presence of contaminants by current isolation methods | ||
| • Present protection for their content |