Leung M, Freidin MB, Freydina DV, et al. - Researchers developed an initial blood-based circulating tumor DNA (ctDNA) gene signature as well as confirmed the clinical test performance among patients having early primary and secondary lung cancer. Blood was donated by 211 patients with known or suspected lung cancer before they underwent surgery, between January 2009 and October 2014, and these patients were observed up to May 2018. Using plasma and corresponding formalin-fixed, paraffin-embedded tissues, ctDNA was extracted. In a blinded manner, blood was examined and pathology reports blinded to the blood test results were issued. There were 192 participants in total, including 95 men (49%). A sensitivity, specificity, positive predictive value, and negative predictive value of 75%, 89%, 98%, and 35%, respectively, were shown in clinical test performance for the blood-based diagnostic signature vs conventional clinical histopathology reporting of the resected tissue. Based on the findings, blood-based ctDNA analysis of cancer mutations was identified as a specific, noninvasive test for cancer diagnosis.