Fig. 3.

The three early cancer detection scenarios. a The detection of relapse after surgery with curative intent is facilitated by the option to profile the resected tumor and to use this information for the design of personalized assay panels, which can be used for high-resolution monitoring approaches. b In individuals at-risk, i.e., due to a cancer-predisposition germline mutation, chronic exposure to toxic agents, or due to viral infections, systemic screening approaches can be extended by proximal sampling, i.e., the analysis of other body fluids than blood which are close to the organ with high-risk of malignant transformation. c In the “general population”, i.e., persons without a family history of cancer or known risks for tumors at certain sites, liquid biopsy concepts for screening may include the search for mutations, somatic copy number alterations, or analyses of methylation and chromatin patterns. However, generally accepted strategies do not yet exist. Naturally occurring phenomena such as the aging associated mutation rate or clonal expansions of non-tumorous tissue may hamper early detection efforts (see also Table 1)