Fig. 1. ctDNA kinetics vary with kinetics of release and degradation/clearance and interact closely with treatment effects.

The interplay of these factors governs the various potential applications of ctDNA along the cancer treatment timeline. Both early transient changes in ctDNA and gradual decay kinetics may be informative of response to treatment. Understanding the implications of these kinetics may inform treatment decisions, allowing for early adjustments. Studies examining ctDNA kinetics vary by how they quantify ctDNA, which time points they sample, what metrics are used to summarize ctDNA kinetics, and which clinical outcomes they collect. WES, whole exome sequencing.