We detected the T790M mutation of EGFR at a frequency of 28.8% in plasma cfDNA of EGFR-TKI–treated patients, a value lower than that reported in a previous study (43%) investigating the digital PCR–based quantification of T790M in plasma cfDNA of patients with advanced NSCLC treated with EGFR-TKIs [15]. Here, EGFR is linked to non-small cell lung carcinoma.