The detection of occult micrometastasis in breast cancer patients may allow the establishment of prognosis and development of new therapeutic approaches. This study was performed in order to improve on existing methods of detection by evaluating the potential of specific mRNA markers in reverse-transcriptase polymerase chain reaction (RT-PCR) of peripheral blood and bone marrow taken from patients with breast cancer.

Peripheral blood and bone marrow samples were obtained from thirty-four breast cancer patients who undergone surgery in the Department of Surgery, Uijongbu St. Mary's Hospital between January 2000 and May 2001. In RT-PCR, we tried multiple primers on breast cancer cell lines and patient samples. Using MUC-1 and CK19 mRNA primers, we detected micrometastasis in breast cancer patients. Subsequently, we analysed the correlation with RT-PCR results and other prognostic factors.

MUC-1 and CK19 were detected in all breast cancer cell lines. However, CEA was not detected in some cell lines. CK19 showed greater sensitivity than MUC-1 in RT-PCR. Using MUC-1 as primers, the detection rate was 47.1% and 35.3% in bone marrow and peripheral blood, respectively. Seven patients (20.5%) were positive in both sources. In the case of CK19, the detection rate was 50% and 41.2% in bone marrow and peripheral blood, respectively. Twelve patients (35.2%), were noted as being positive for both primers. The concordance rate of both primers mers was 38.2% and 23.5% in bone marrow and peripheral blood, respectively. CK19 positivity in the peripheral blood was correlated with bone marrow positivity and MUC-1 positivity in both sources and inversely correlated with ER. CK19 positivity of bone marrow was correlated with MUC-1 positivity of bone marrow.

CK19 and MUC-1 may be good candidates for use in RT-PCR for the detection of micrometastasis of breast cancer. CK19 showed greater sensitivity. However, using both primers in RT-PCR, we may detect micrometastasis more sensitively and specifically and more wisely choose a treatment modality.