In our samples of patients with stage T1–4N0–2M0 HNSCC, the median levels of CAP1, CFL1, and PFN1 in the serum were 0.10 ng/mL (IQR 0.07–0.15 ng/mL), 0.47 ng/mL (IQR 0.37–0.82 ng/mL), and 0.32 ng/mL (IQR 0.25–0.42 ng/mL), respectively. This evidence concerns the gene PFN1 and head and neck squamous cell carcinoma.