Figure 3. Rationale for increasing genome equivalents versus increasing the number of tracking mutations to identify ctDNA.

In this example, the tumor/cancer cells have six distinct mutations (colored stars) that are being shed into the circulation along with normal DNA from normal cells (in blue). If an assay only queries for a single mutation, then a large amount of DNA is required to ensure a high likelihood that the mutation will be in the sample (bottom left). On the other hand, if plasma DNA is limited, then there may be only a single mutation in the sample (green star), and therefore querying for all DNA mutations is needed such that there is high likelihood that any mutation will be identified (bottom right).