Carcinogenesis is accompanied by deregulated tumor cell death and changes in proliferative processes. Apoptotic cells release different components, such as nucleosomes and caspases, into the blood circulation that can be detected by minimally invasive assays. Caspases belong to a large family of proteases, which are frequently overexpressed in various cancer entities and involved in metastases. One critical event of tumor invasion that signals the initiation of the metastatic cascade is the degradation of basement membrane components by protease supporting invasive cell migration and the dissemination of tumor cells.
