Table 4.
Summary of selected CellSearch-based studies comparing circulating tumour cell numbers with radiological outcomes and overall survival.
| Study and cancer Type | Breast [Budd et al. 2006] | Breast [De Giorgi et al. 2009] | CRC [Cohen et al. 2008] | CRC [Tol et al. 2010] | Breast [Nakamura et al. 2009] | Breast [Liu et al. 2009] |
|---|---|---|---|---|---|---|
| Number of patients | 138 | 102 | 364 | 307 | 107 | 68 |
| Imaging technique | CT | PET-CT | CT | CT | CT | CT |
| Timing of imaging from baseline | 10 weeks | 9–12 weeks | 6–12 weeks | 9 weeks | 12 weeks | 9–12 weeks |
| Timing of CTC from baseline | 4 weeks | 9–12 weeks | Within 1 month imaging/death | 1–2 weeks | 3–4 weeks | 3–12 weeks |
| CTC cut off | 5 | 5 | 3 | 3 | 5 | 5 |
| Concordance (% patients with <cut off CTC and NPD by imaging and patients with ≥ cut off CTC and PD by imaging) | 76% | 75% | 78% | 90% | Not reported | 70% |
| Median OS according to Imaging and CTC parameters: | ||||||
| 1. NPD by Imaging and CTC <cut off | 26.9 m | Not reached | 18.8 m | 21.6 m | Not reported | Not reported |
| 2. PD by Imaging and CTC <cut off | 19.9 m | 14.7 m | 8.3 m | 7.1 m | ||
| 3. NPD by Imaging and CTC ≥cut off | 15.3 m | 4.9 m | 7.1 m | 9.4 m | ||
| 4. PD by Imaging and CTC ≥cut off | 6.4 m | 9.8 m | 3.1 m | 3.4 m | ||
| Statistical significance between groups: | ||||||
| 1v2 | 0.0785 | 0.0018 | <0.0001 | <0.0001 | Not reported | Not reported |
| 1v3 | 0.0389 | <0.0001 | <0.0001 | <0.0001 | ||
| 1v4 | <0.0001 | <0.0001 | <0.0001 | <0.0001 | ||
| 2v3 | 0.7549 | 0.1073 | 0.4662 | Not reported | ||
| 2v4 | 0.0039 | 0.2244 | 0.0001 | Not reported | ||
| 3v4 | 0.0777 | 0.6441 | 0.0330 | Not reported | ||
| Additional comments | CTCs strongest predictor for OS in multivariate analysis. However, both CTC values and imaging were useful in combination in predicting survival outcome. | CTCs strongest predictor for OS in multivariate analysis. In this series imaging helpful in determining prognosis in patients with <5 CTCs. In patients with ≥ 5 CTCs, difference in survival was not significant between those with PD or NPD by imaging | CTCs strong predictor for OS in multivariate analysis. However, both CTC values and imaging were useful in combination in predicting survival outcome | CTCs at baseline and at 1–2 weeks, strongest predictor for PFS and OS in multivariate analysis. However, both CTC values and imaging were useful in combination in predicting survival outcome | In cases where CTCs increased at 3–4 weeks, 63.6% patients showed PD at time of CT scan. In cases where CTCs decreased by >90% at 3–4 weeks, 85.7% patients showed complete or partial response at imaging | If ≥5 CTCs detected at time of imaging, 3–5 weeks prior to imaging or 7–9 weeks prior to imaging, Hazard Ratio for PD at scan = 6.3, 3.1, 4.9 respectively (p < 0.001). Study included patients on hormonal therapy as well as chemotherapy |
FU, follow up; OS, overall survival; PD, progressive disease; NPD, nonprogressive disease (defined as combination of complete response, partial response and stable disease); CTC, circulating tumour cell; CRC, colorectal cancer.