Abstract: The present invention provides methods for improving the treatment effect of a chemotherapy regimen of a patient suffering from HER2 positive breast cancer, in particular locally recurrent or metastatic HER2 positive breast cancer, by adding bevacizumab (Avastin®) to a chemotherapy regimen by determining the expression level, in particular the blood plasma expression level, of E-selectin, ICAM-1 or VEGFR-3 relative to control levels of patients diagnosed with HER2 positive breast cancer, in particular locally recurrent or metastatic HER2 positive breast cancer.