Ding PN, et al. - Three blood-based biomarkers-circulating tumor DNA (ctDNA), circulating tumor cells (CTC) and carcinoembryonic antigen (CEA)- were investigated for their predictive and prognostic roles in patients with advanced epidermal growth factor receptor-mutated (EGFR+) lung cancer. Recruitment of 28 patients with 103 serial blood samples was done. Findings suggested high concordance of EGFR mutation detection in plasma with tissue biopsy. Higher disease burden was noted in relation to detectable baseline ctDNA. Researchers observed radiological response at 12 weeks of treatment and improved progression-free survival (PFS) and overall survival (OS) in correlation to early disappearance of ctDNA at 4 weeks. Improved PFS but not OS was noted in relation to a decrease in CTC count at 4 weeks. A ctDNA rise was observed in 85% of patients with radiological progression vs 22% of patients with stable disease. On average 170 days prior to radiological progression, rise in ctDNA was noted. A significant correlation of the rise of CEA level with radiological progression was observed. These findings suggest the long term predictive value of early change in ctDNA, CTC and CEA levels for treatment benefit and failure prior to availability of radiological response data.