The Liquid Biopsy, What is it, How is it Provided, and What is the Role of the Pulmonologist

Abstract

Non–small cell lung carcinoma represents the most common form of lung cancer, which itself is the cancer responsible for most deaths annually worldwide. In the advances toward personalized medicine in cancer care, the liquid biopsy is the most recent leap forward allowing treatment based upon driver mutations harbored within a patient. Cell free DNA (cfDNA) is shed from cells within the body, and the tumor cells are no different. This circulating tumor DNA can be sampled and tested for therapeutic and diagnostically actionable genes and gene mutations. Because of the relatively uncommon nature of these circulating tumor DNA, the available tests are designed to have very high sensitivity, with the tradeoff of a more modest specificity. The data supporting the major commercially available liquid biopsies are reviewed and summarized. The most common use of the liquid biopsy is to test for actionable mutations, but other uses include monitoring for disease progression and testing for resistance mutations in patients undergoing treatment.