EGFR and neoplasm: Activating Tumor Mutations: 88.2% of tumor samples had EGFR mutations; 58.8% of plasma cfDNA samples had EGFR mutations.Resistance Mutations: T790M mutation in plasma cfDNA detected in patients after receiving EGFR-TKIs; 81.8% sensitivity, 85.7% specificity, 83.3% concordance between plasma cfDNA and tumor tissue