Potential role of circulating tumor cell and cell-free DNA from liquid biopsy as biomarker in oral squamous cell carcinoma

Metastasis in patients with oral squamous cell carcinoma has been associated with a poor prognosis. Circulating tumor cells and cell-free DNA are becoming promising biomarkers of solid tumors such as breast cancer and colorectal cancer. Hence, this study aimed to determine the potential role of liquid biopsy, circulating tumor cells, and cell-free DNA as biomarkers of oral squamous cell carcinoma. Thirteen patients with primary oral squamous cell carcinoma who visited the Department of Oral Oncology at Hiroshima University Hospital between 2022 and 2023 were recruited. Plasma samples were collected from each patient before and after the surgery. We examined the relationship between the prognosis, the number of circulating tumor cells per four milliliters of peripheral blood, and the amount of cell-free DNA per milliliter of serum or the gene mutation in cell-free DNA. In our sample, no correlation was observed between the number of preoperative circulating tumor cells and metastatic events. However, the number of circulating tumor cell clusters or the amount of preoperative cell-free DNA in metastatic cases was higher than that in non-metastatic cases. In oral squamous cell carcinoma, cell-free DNA levels may help inform management decisions regarding metastasis.