The “liquid biopsy” in non-small cell lung cancer—not quite ready for prime time use

Biopsy of a tumor site has long been the gold standard for the diagnosis of malignancy. Advanced sequencing technology has enabled us to study the molecular changes driving a particular cancer. As we move towards the molecular era of medicine, repeat tumor biopsies are often obtained to assess for development of resistance, which has both prognostic and therapeutic implications. However, the logistics of obtaining repeat tumor biopsies are complicated—many patients with advanced malignancies are unable or unwilling to undergo another invasive procedure and the skillset and personnel required for these procedures are often time consuming, expensive, and leads to delay in care. Furthermore, it is known that tumors develop heterogeneity over time and disease sites and therefore one biopsy may not provide a complete picture of the tumoral landscape.