Cell-Free DNA (cfDNA), Its Applications in Cancer Diagnosis and Monitoring, and Its Potential Role in Regulating Cancer Metabolism.

Cell-free DNA (cfDNA) has emerged as a valuable biomarker in cancer diagnosis, monitoring, and prognosis. cfDNA refers to small fragments of DNA that are released into the bloodstream from tumor cells, normal cells, or dying cells within the body. In the context of cancer, circulating tumor DNA (ctDNA), a subset of cfDNA, contains tumor-specific genetic mutations, epigenetic alterations, and structural variations that can be used to detect the presence of cancer, track disease progression, and assess therapeutic response. Beyond its diagnostic potential, cfDNA plays a significant role in the regulation of cancer cell features and potentially cancer metabolism. Recent studies suggest that cfDNA is not merely a passive byproduct of cellular turnover but may actively influence tumor microenvironments, inflammation, and metabolic pathways, thereby impacting cancer progression. This review explores the clinical utility of cfDNA in cancer, its emerging role in metabolic regulation, and its potential to transform personalized cancer therapy by providing non-invasive, real-time insights into tumor dynamics.