Patients with head and neck squamous cell carcinoma (HNSCC) have a high risk of metastasis and recurrence, and aberrant activation of PI3K/AKT/mTOR signaling occurs in approximately 80% of HNSCC, which has been suggested as a prognostic biomarker for patients with recurrence or metastasis (139). Here, MTOR is linked to head and neck squamous cell carcinoma.