Breast cancer is the leading cause of cancer death in females [1],and metastasis of this malignancy attributes mainly to the death.Investigations have shown that metastasis occurs mostly through the lymphatic pathway,thus the status of lymph nodes plays a pivotal role in determining the prognosis.However,clinicians routinely use axillary and sentinel lymph node biopsy,which has drawbacks with respect to severe complications (e.g.lymphedema) and invasiveness.To find potential assays which are less invasive and more specific is of great clinical importance.