Our study did not calculate the portion of T790M-positive patients among all EGFR-TKI-naïve patients, but previous studies estimate that T790M can be found in around 2% of EGFR-activating mutation-positive EGFR-TKI-naïve plasma samples [19] and frozen tumor samples [20]; however, the percentage can be much higher (>40%) in FFPE tumor samples, likely due to higher incidence of false positives [20]. This evidence concerns the gene EGFR and neoplasm.