Interest of Circulating Tumor DNA in Digestive and Gynecologic/Breast Cancer

Circulating tumor DNA (ctDNA) offers the possibility of accessing the tumor genome from circulating blood through a simple blood test. It is currently used for diagnostic, prognostic and predictive purposes of response or resistance to oncological treatments. These advances in ctDNA have been made possible by major developments in molecular biology techniques in recent years, as the detection of ctDNA requires very sensitive techniques such as Next Generation Sequencing (NGS). CtDNA overcomes this problem of very limiting tumor heterogeneity during a solid biopsy. All of these applications make circulating DNA an increasingly essential tool in the management of cancer patients. The studies are currently in most cases on small numbers and are retrospective. In addition, exosomes are also a biomarker of the future that can also be detected in the bloodstream . Exosomes are nanovesicles 50 to 200 nm in diameter released into the extracellular environment via the endosomal pathway by fusion with the plasma membrane. They are very informative since they transport tumor genetic material in the form of DNA, mRNA and miRNA, but also adhesion proteins, immunostimulatory molecules and cytoskeleton, enzymes and Heats shock proteins ( HSP). The aim of the ADIGYN study is to set up a large prospective cohort to assess the diagnostic, prognostic and predictive impact of ctDNA and exosomes in digestive and gynecological / breast cancers. From the circulating DNA, we characterize the ActDNA on the molecular level thanks to the study of different point mutations usually used but also of new described mutations having a therapeutic impact and the search for other genetic alterations having an impact on the therapeutic strategy (such as microsatellite instability) or the study of exosomes and their composition. To assess resistance to oncological treatments, ctDNA will be analyzed at the start of treatment, during treatment, during progression and / or relapse and also during monitoring or treatment break