Immunodetection of breast cancer cells in bone marrow for monitoring high-dose sequential chemotherapy

The immunodetection of breast-cancer cells in bone marrow may be a useful technique for monitoring the efficiency of chemotherapy in selected clinical settings. We used monoclonal antibodies against cytokeratins and an epithelial membrane antigen pool to detect microscopic metastatic deposits in bone marrow aspirates from a high-risk patient before and after high-dose sequential chemotherapy. In the slides done before therapy, 250 immunostained cells were found, but only 20 immunostained cells were found in slides made after chemotherapy. Moreover, double-staining procedures showed consistent colocalization of the two markers on the same cancer cells. A fraction of the micrometastatic cells were additionally immunostained for Ki-67, a well-established marker of cell proliferation. These data suggest that the immunodetection of breast cancer cells in bone marrow may have potential clinical implications in the management of high-risk breast cancer.