Molecular residual tumor monitoring in solid cancers

Blood-based diagnostics has long been used in the oncological practice of solid tumors, but its full potential is just unfolding recently. Quantitative measurement of tumor markers, circulating tumor cells, and some of their products or components have now become available and are part of a multimodal system that provides additive parameters in clinical decision making. The most challenging oncological questions can be answered by the detection, characterization and measurement of circulating free DNA (cfDNA), which, due to its growing importance, bears the potential of incorporation into routine practice. In this overview, we review the „blood impressions” of solid tumors and present the most promising results in different patient groups, especially in lung, breast, colon, and bladder tumors, which are also valid for other solid tumors.