Metastasising tumour disease is the main cause of mortality in oncologic patients. In the majority of breast tumours the first place of metastases are regional lymph nodes. But the tumours can metastasise also via haematogenic route even in the early stage. Circulating tumour cells are the part of micrometastatic disease. Detecting of its presence can have prognostic importance and from the view of therapeutic procedures it can be used in individualizing of oncologic patient treatment.