Figure 2.

ctDNA as a biomarker in oral and oropharyngeal squamous cell carcinoma. This figure illustrates the circulation of tumor-related materials in the bloodstream relevant to oral squamous cell carcinoma (OSCC) and head and neck squamous cell carcinoma (HNSCC). The tumor releases necrotic tumor cells, macrophages, circulating tumor cells (CTCs), and circulating tumor DNA (ctDNA) into the bloodstream, shown alongside red blood cells. Macrophages as immune cells interact with these tumor components. CTCs are live tumor cells that have shed into the bloodstream, and ctDNA consists of fragments of tumor DNA circulating in the blood. These materials represent various stages of tumor cell degradation and dissemination, with ctDNA a potential cancer detection and monitoring biomarker. The figure highlights the complexity of tumor biology and the potential for blood-based biomarkers in diagnosing and monitoring OSCC and HNSCC.