The Micrometastasis and cancer stem cell group studies various aspects of the metastatic process, with special focus on disseminated tumor cells in the bone marrow (DTC), circulating tumor cells in peripheral blood (CTC), cancer stem cells and recently also circulating cell-free tumor DNA (ctDNA). It is expected that DTC/CTC will be useful both as prognostic and predictive indicators for cancer patients, for early prediction of relapse, as tools for monitoring of therapy, and as basis for individually tailored therapy. The clinical relevance of DTC/CTC has been demonstrated in a high number of publications, among them large pooled analyses for early breast cancer. Interventional clinical studies have been initiated during the last years, evaluating therapy choices based on DTC/CTC presence. There is increasing evidence for the cancer stem cell properties of DTC/CTC. The Stem cell laboratory headed by Z. Suo has years of experience in, and infrastructure for, the study of cancer cell stemness regulation, typically influenced by hypoxia and metabolic intermediates. There are novel cancer treatment studies, especially by using gene knockout cell lines and gene knockout animal models for such purposes. Based on these models, novel circulating tumor cell capturing and targeting modalities are in development as well.