Extrachromosomal DNA in Non-Invasive Cancer Diagnostics

The journey from gene to genome has expedited the understanding of varied mechanisms that manifest the story of genomic instability in the formation of extrachromosomal DNAs (ecDNAs). These ecDNAs are double-stranded circular DNAs found in eukaryotes. It emerged as a transformative biomarker in non-invasive cancer diagnostics, offering insights into tumor heterogeneity, progression, and treatment resistance. Advanced use of deep-based machine learning and next-generation sequencing (NGS) emphasizes the impact of ecDNA in plasma, providing a cost-effective and longitudinal approach in monitoring the cancer dynamics without invasive tissue biopsies. This chapter comprehensively illustrates the unique properties of the ecDNAs or cell-free DNA, as a consequence of genomic anomaly, its detection, and subsequent mapping in the bloodstream. Newer possibilities for the ecDNA amplification mark a pivotal role as a non-invasive biomarker or a checkpoint for early diagnosis and prognosis in major cancer types. Thus, ecDNA underlines the treatment efficacy with a new paradigm shift as a potential non-invasive personalized cancer diagnostic biomarker.