Minimal residual disease in bone marrow and peripheral blood of patients with metastatic breast cancer.

The presence of occult micrometastases in bone marrow (BM) of patients with early breast cancer increases the risk of relapse. Detection of circulation tumor cells in peripheral blood (PB) may also influence the patient's prognosis. Few data are available on the correlation between tumor cell dissemination in BM and PB in solid epithelial tumors. Twenty-milliliter blood samples were collected from PB of 42 patients with advanced breast cancer and centrifuged using the density gradient OncoQuick (OncoQuick Greiner BioOne, Frickenhausen, Germany). The BM aspirates available from 11 of the 42 patients were centrifuged using density centrifugation Ficoll. Tumor cell detection was performed by microscopy after cytospin preparation and immunocytochemical staining with the monoclonal antibody A45-B/B3. Cytokeratin-positive cells were detected in 23 patients (55%) in the PB and in three patients (27%) in the BM. A cohort with bone lesions as the only metastatic side showed a correlation as follows: 7 of the 11 patients (64%) had negative findings in BM and PB, whereas cytokeratin-positive cells in PB were present in 3 of these 11 patients (27%). The presence of visceral metastases was associated with the detection of cytokeratin-positive cells in the PB in 20 of the 31 patients (65%) in this subgroup. The density gradient OncoQuick in combination with immunocytochemical staining allows the detection of cytokeratin-positive cells in PB of patients with advanced breast cancer. The immunocytochemical detection of cytokeratin-positive cells in PB seems to be associated with the site of metastatic manifestation.