Purpose: Detect cytokeratin 19 mRNA(CK-19 mRNA) in nucleated cells in peripheral blood from breast cancer. To establish a diagnostic method for breast cancer metastasis in peripheral blood. Methods: Peripheral blood samples in breast cancer patients (test group, n = 66) and benign tumour in breast patients ( control group, n = 37) were taken. Then, the nucleated cells were separated and total RNA extracted, and CK-19 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) technique. Re...