ESR1 and neoplasm: Interestingly, we detected WBC variants in DNMT3A, TP53, ERBB4, MLH1, PDGFRA, FGFR3, ESR1, IDH2, and ATM among multiple timepoints analyzed in 11 patients that did not harbor any tumor-specific alterations in cfDNA (Supplementary Fig. 4b–l).