[Minimal residual disease in breast cancer: detection and clinical relevance]

Hematogenous distant metastasis is the leading cause of cancer-related death in breast cancer and other solid tumours. By applying sensitive immunocytochemical and molecular assays disseminated tumour cells (DTC) in bone marrow (BM) can be detected in 20-40% of cancer patients without any clinical or even histopathological signs of metastasis. The detection and characterisation of DTC in BM may lead to a better understanding of the biology initiating metastatic spread in cancer patients and will eventually contribute to the development of more effective strategies to eliminate DTC. In this review, we will therefore discuss the detection, characterisation and clinical relevance of DTC.