Circulating Tumor DNA: A Pan-Cancer Biomarker in Solid Tumors with Prognostic and Predictive Value

Circulating tumor DNA (ctDNA), often referred to as a liquid biopsy, represents a promising biomarker in the management of both localized and advanced solid tumors. It has garnered significant attention due to its potential to inform prognosis and guide therapeutic decisions. The clinical utility of ctDNA spans early cancer detection, minimal residual disease identification, recurrence surveillance, treatment monitoring, and precision oncology treatment decision-making in the advanced setting. Unlike conventional radiological assessments, the short half-life of ctDNA allows for more timely insights into disease dynamics. Several technological approaches are available to measure ctDNA, including next-generation sequencing and droplet digital polymerase chain reaction, although their clinical accuracy depends on multiple biological and technical factors. This review evaluates current evidence surrounding ctDNA's utility in early and advanced solid tumors.