Detection of bone marrow micrometastases by reverse-transcriptase polymerase chain reaction (RT-PCR) in patients with early breast cancer

OBJECTIVES The aim of this study was to determine the feasibility of a molecular assay by investigating cytokeratin 19 (CK-19) and DF3 gene expressions in detection of occult cancer cells in bone marrow in patients with breast cancer. METHODS Transcriptase-polymerase chain reaction (RT-PCR) assays were carried out for the detection of CK19 and DF3 mRNA transcripts in bone marrow samples of 28 clinically axillary negative patients with early breast cancer. RESULTS Median age of patients was 47.5 (range, 32-86). Due to the high false positivity rate of the CK19-RT-PCR assay, and negative findings by the DF3-RT-PCR assay in bone marrow samples of patients with chronic myelogenous leukemia as negative controls, DF3 expression was tested in further RT-PCR assays. Eighteen patients (64%) were found to harbor DF3-positivity in bone marrow samples. No statistically significant associations could be found between DF3-positivity and other parameters including stage, tumor size (<2 cm vs >2 cm), axillary involvement, ER/PR positivity, and high histologic or nuclear grade. CONCLUSION Our results suggest that testing DF3 expression by RT-PCR technique seems to be a reliable method in detection of micrometastatic cells in bone marrow in patients with early breast cancer because of its high specificity.