Clinical Interest of Circulating Tumor DNA in Oncology

Genetic alterations in tumors, as predictor of response to targeted-therapies or as prognostic markers, are clinically relevant to determine adequate therapeutic management. Tumor biopsy is currently the golden standard for somatic alterations assessment, but this approach is invasive and does not consider tumor heterogeneity. In various body fluids like plasma, somatic mutations have been identified. Circulating tumor DNA (ctDNA) holds promises in tumor burden monitoring or malignancies early detection. Since allele frequencies of circulating somatic mutations are low, highly sensitive novel assays have been developed to allow the investigation of the tumor genome, leading to the emergence of the "liquid biopsy" concept. Despite these technological advances, other assays for identifying intratumor and intermetastases heterogeneity need to be developed. Before being applied to clinic, ctDNA analyses need to be harmonized and validated with well-powered, well-designed studies. One of the primary prerequisite to incorporation of ctDNA analysis in the follow-up strategy of malignancies is the checking of the concordance with golden standard detection methods, imaging, circulating proteins and biopsy. This review focuses on the clinical interest of ctDNA in solid tumors and hematological malignancies.