Abstract
Circulating tumor DNA (ctDNA), a newly developed cancer biomarker, consists of single- or double-stranded DNA fragments that are shed from tumor cells in primary or metastatic sites. They are released into peripheral blood and exhibit distinct characteristics associated with cancer, even in the early stages. With advancements in technology, ctDNA detection has become more diverse and precise, including digital Polymerase Chain Reaction (dPCR) and next-generation sequencing (NGS), among others. As a chronic disease that develops over an extended period, early detection is crucial for the accurate diagnosis and treatment of cancer and can significantly improve patient prognosis. Therefore, analyzing ctDNA features is important. Additionally, ctDNA can be used to assess post-surgical minimal residual disease (MRD), aiding in treatment decisions. Overall, ctDNA plays a crucial role in the progression of cancer and its treatment. This review summarizes the sources and features of ctDNA, the analytical techniques used, and its application in both solid and non-solid tumors.