Table 1.
Most frequently investigated biomarkers of all studies included.
| Biomarker * | Number of Articles | % of Included Studies | End Stage | Number of Studies at End Stage |
|---|---|---|---|---|
| ALDH1 | 5 | 1.6% | Observational | 1 |
| CA15-3 | 51 | 15.9% | Observational | 6 |
| CEA | 19 | 5.9% | Observational | 1 |
| CK19 | 6 | 1.9% | Observational | 1 |
| CTC enumeration | 154 | 48.1% | Clinical trial | 29 |
| EGFR | 15 | 4.7% | Observational | 6 |
| ER | 13 | 4.1% | Basic prognostic | 3 |
| HER2 | 61 | 19.1% | Observational | 15 |
| PIK3CA | 13 | 4.1% | Observational | 1 |
| PR | 7 | 2.2% | Basic prognostic | 2 |
| RASSF1A | 6 | 1. 9% | Basic predictive | 5 |
| THBS-1 | 9 | 2.8% | Observational | 5 |
| TP53 | 5 | 1.6% | Basic prognostic | 1 |
| TWIST | 7 | 2.2% | Observational | 2 |
| VEGF | 22 | 6.9% | Observational | 15 |
| VEGFR | 13 | 4.1% | Observational | 12 |
| Vimentin | 6 | 1.9% | Basic prognostic | 1 |
* The abbreviations used are standard abbreviations. Corresponding gene identities encoding for these biomarkers are presented in Appendix D.