Detection of disseminated tumor cells in peripheral blood of patients with breast cancer: correlation to nodal status and occurrence of metastases.

Soon after breast cancer becomes invasive, it sheds cancer cells into the blood stream or the cancer cells are spread via lymphatic vessels. The early and unambiguous detection of these disseminated tumor cells (DTC) is of importance for the evaluation of the tumor process and for monitoring therapy response. The detection of disseminated tumor cells by immunocytochemistry (ICC) without previously performing tumor cell enrichment is time consuming and may miss a considerable part of these cells. Therefore, we have applied a negative immunomagnetic enrichment of disseminated tumor cells from the peripheral blood of patients with breast cancer by the depletion of CD45(+) leukocytes using automated magnetic activated cell separation (autoMACS). One hundred twenty-five blood samples from 83 breast cancer patients were investigated for occurrence of disseminated tumor cells by autoMACS technique and immunocytochemical cytokeratin staining. Frequency of disseminated tumor cells was analyzed statistically for correlation to clinical data. Thirty-three of the 125 blood samples (26%) originating from 29 of 83 breast cancer patients (35%) carried cytokeratin positive (CK(+)) tumor cells. The occurrence of CK(+) tumor cells correlated significantly with the nodal status (P = 0.009) and with the occurrence of metastases at the time of primary tumor resection (P = 0.003). The finding that occurrence DTC detected in peripheral blood of breast cancer patients correlated with nodal stage and metastases is described for the first time. It suggests that disseminated tumor cells identified in peripheral blood by autoMACS are associated with tumor characteristics of breast cancer.