The predictive and prognostic significance of liquid biopsy in advanced epidermal growth factor receptor-mutated non-small cell lung cancer: A prospective study

•ctDNA decrease at one month was an early predictor for radiological response.•Patients with CTC and ctDNA decrease had better survival outcomes.•ctDNA and CEA rise preceded radiological evidence of disease progression.•Mutation detection in ctDNA was highly concordant compared with tissue biopsy. To determine the predictive and prognostic roles of three blood-based biomarkers: circulating tumour DNA (ctDNA), circulating tumour cells (CTC) and carcinoembryonic antigen (CEA), in patients with advanced epidermal growth factor receptor-mutated (EGFR+) lung cancer. We recruited 28 patients with 103 serial blood samples. We performed mutational analyses for EGFR mutations using droplet digital PCR (ddPCR) on ctDNA. We evaluated the accuracy of EGFR mutation detection in ctDNA compared with tissue biopsy. We also quantified CTCs, ctDNA and CEA in serially collected blood samples, and evaluated the baseline and changes in these blood-based biomarkers with clinical outcomes. EGFR mutation detection in plasma was highly concordant as compared with tissue biopsy. Detectable baseline ctDNA was associated with higher disease burden (p