Circulating free DNA, new dynamic marker in nonsmall cell lung cancer patients?

Platinum-based doublet chemotherapy prolongs survival and improves quality of life as first-line treatment for non-selected and good performance status patients with advanced nonsmall cell lung cancer (NSCLC) [1]. However, the survival benefit is limited, even if this combination is the standard of care for decades, no clinically relevant predictive biomarkers have been discovered so far. The identification of surrogates for survival is an important topic for cancer therapy selection. Indeed, overall survival is still the best criterion for predicting treatment efficacy in lung cancer but it can, of course, not be used in clinical practice. In a recent systematic review of the literature, some intermediate criteria have been shown to be potentially useful predictors such as time to progression, progression-free survival, objective response, local control after radiotherapy, downstaging in locally advanced NSCLC, complete resection and pathological TNM (tumour, node, metastases) in resected NSCLC or circulating molecular markers or cells. Retrospective studies have suggested that carcinoembryonic antigen, cytokeratin 19 fragments, pro-gastrin-releasing peptide and, to a lesser extent, neuron specific enolase, cancer antigen 125 and cancer antigen 19-9, used as single criterion to assess overall survival, could be adequate intermediate criteria for survival in lung cancer patients [2]. The use of more sophisticated molecular markers developed thanks to recent progresses in molecular biology has also so far not been successful for that purpose even if high throughput techniques are used such as transcriptomic analyses assessing multiple miRNAs and mRNAs [3].