Table 1 Summary of clinical trials reviewed that served to validate the predictive and prognostic capability of CTCs

1. Multi-institution, double-blind, clinical trial of patients with MBC with measurable disease beginning a new therapy. CTCs assessed at baseline and at 1^st follow-up clinical visit, approximately 3-4 weeks after starting therapy.¹⁴

PFS, OS

Prospective

177

Any

7.0 vs 2.7; p < 0.001 baseline assessment 7.0 vs 2.1; p < 0.001 1^st follow-up

>18 vs 10.1; p < 0.001 baseline assessment >18 vs 8.2; p < 0.001 1^st follow-up

2. Multi-institution, double-blind, clinical trial of patients with MBC with measurable disease on treatment. CTCs assessed at 2^nd follow-up and subsequent follow-up clinical visits up to 9 months of follow-up. Sub-study of #1 above.¹⁵

PFS, OS

Prospective

177

Any

5.6 - 7 vs 1.3 - 6; p = n/a

18.6- >25 vs 6.3 - 10.9; p = 0.001

3. Multi-institution, double-blind, clinical trial of patients with MBC with measurable disease beginning a new therapy. CTCs assessed at baseline and 1^st follow-up clinical visit, approximately 3-4 weeks after starting therapy for the 47% of patients who were being treated with 1^st line palliative therapy. Sub-study of #1 above. ¹⁶

PFS, OS

Prospective

83

1^st line

9.5 vs 4.9, p = 0.0014 baseline assessment 9.5 vs 2.1, p = 0.0057 1^st follow-up

>18 vs 14.2, p = 0.0048 baseline assessment >18 vs 11.1, p = 0.0012 1^st follow-up

4. Single institution, retrospective analysis of a cohort of newly diagnosed MBC patients (either with de novo MBC or newly diagnosed recurrent MBC) who had CTCs assessed at the time of initial diagnosis of MBC between 2001 and 2007. CTCs assessed at baseline, prior to starting salvage therapy.¹⁷

OS

Retrospective

185

1^st line

28.3 vs 15, p < 0.001

5. Single institution assessment of a cohort of MBC patients prior to starting a new treatment regimen. CTCs assessment correlated with histology and phenotypic subtypes of breast cancer.¹⁸

Exploratory OS

Retrospective

517

Any