The clinical relevance of the demonstration of isolated cancer cells in bone marrow and blood from patients with primary breast cancer

Data is emerging on the prognostic relevance of occult metastatic cells in the bone marrow of patients with various solid tumors. There is increasing evidence that validated anti-cytokeratin antibodies represent the present standard for the detection of isolated tumor cells. This immunocytochemical assay allows the identification of patients with occult tumor cell dissemination that cannot be identified by conventional screening methods in tumor staging. According to recent studies, these patients are at higher risk for the subsequent development of distant metastases and might therefore benefit from early systemic therapy. Therapeutic monitoring and cell cycle independent antibody-based therapy are among the possible implications of this new, promising diagnostic tool. The present review also focuses on the state of the art in reliable detection methods of occult metastatic cells in the bone marrow of breast cancer patients and on the prognostic relevance of these cells at different stages of the disease. © 2007 Springer Medizin Verlag.