LAUSR

Non-invasive liquid biopsies may transform the management of patients with cancer. Circulating tumour DNA (ctDNA) derived from cancer cells can be identified in most patients with advanced cancer, representing a potential non-invasive source of tumour DNA. The analysis of ctDNA may be useful to genotype the cancer, to select treatment options and to monitor response to treatment. ctDNA is often at a low level in plasma, requiring highly sensitive and accurate assays for ctDNA analysis. ctDNA was detected and profiled together with primary tumour DNA obtained from surgical specimens in 40 patients with lung cancer with localised disease who were diagnosed at stages I–III and operated on with curative intent. In a study carried out by investigators at the University of Stanford and recently published in Cancer Discovery,1 more than 90% of relapsing patients were found to have ctDNA 1 month after resection. This indicates a valuable detection of minimal residual disease. Moreover, ctDNA was able to show residual disease earlier than 5 months, compared with conventional follow-up imaging. The most frequently detected mutations in surveillance samples included mutations in TP53, KRAS, EGFR and KEAP1. Patients with detectable ctDNA at any post-treatment time point had significantly lower freedom from progression and survival than those in whom ctDNA was not detectable after completion of therapy. These findings suggest that ctDNA analysis is a promising approach for minimal residual disease detection in patients with localised lung cancers and that it can identify recurrence significantly earlier than routine CT imaging. The sensitivity and specificity of this diagnostic approach for detecting ctDNA were very high. In this series, all patients with detectable …