Table 2. Comparison of methodologies for ctDNA analysis.
| Method | Technology | Sensitivity | Type of Alteration |
|---|---|---|---|
| qPCR | ARMS-Scorpions PCR | 0.05–0.1% | Known point mutation |
| Clamping PCR | 0.1–1% | ||
| TaqMan | 0.1–1% | ||
| Digital PCR | Beaming | 0.01% | |
| ddPCR | 0.001% | ||
| Target sequencing | TAm-Seq | >2% | Point mutations in gene regions; structural alterations in gene regions |
| SAFE-SeqS | 0.1% | ||
| CAPP-Seq | 0.01% | ||
| Whole genome sequencing | Digital karyotyping | 0.001% | Genome-wide copy-number changes; personalized |
| PARE | 0.001% | genome-wide rearrangements |
ARMS, amplification refractory mutation system; BEAMing, beads, emulsion, amplification, magnetics; CAPP-Seq, cancer personalized profiling by deep sequencing; ddPCR, droplet digital PCR; PARE, parallel analysis of RNA ends; qPCR, quantitative PCR; SAFE-SeqS, safe-sequencing system; TAm-Seq, tagged-amplicon deep sequencing.