Table 6 Progression-free survival analysis of metastatic breast cancer patients, showing the p value, hazard ratio and the 95% confidence interval for this hazard ratio. Stratified or normalized continuous biomarkers used as variables. Univariate and multivariate analysis

 CTC threshold

0.014

1.621

1.102

2.384

Univariate

Stratified biomarker

 cfDNA threshold

0.026

1.555

1.055

2.292

 CA15-3 threshold

0.011

1.607

1.113

2.319

 AP threshold

0.034

1.556

1.034

2.340

 CTC threshold

0.623

1.130

0.694

1.839

*Multivariate

 cfDNA threshold

0.171

0.731

0.467

1.145

 CA15-3 threshold

0.072

1.451

0.967

2.176

 AP threshold

0.461

1.187

0.753

1.872

 CTC count

0.025

3.508

1.172

10.499

Univariate

Normalized continuous biomarker

 cfDNA yield

0.013

1.233

1.045

1.455

 CA15-3 levels

0.066

1.173

0.990

1.389

 AP levels

0.037

1.220

1.012

1.471

 CTC count

0.184

2.401

0.660

8.738

*Multivariate

 cfDNA yield

0.042

1.193

1.007

1.415

 CA15-3 levels

0.311

1.105

0.911

1.339

 AP levels

0.236

1.140

0.918

1.415