We detected the presence of EGFR T790M mutation in the isolated ctDNA (Figure 1C) as well as the EGFR exon 19 deletion using allelic-specific PCR (ASPCR) and Sanger sequencing on single cells isolated from a lung cancer patient with known EGFR exon 19 deletion mutation (Figures 1D, E) using this workflow, proving the capability of the technology for this purpose that is in concordant with previously reported studies from other cohorts of lung and breast cancer patients (7, 23). Here, EGFR is linked to breast cancer.