One study, based on the seventh edition of UICC (Union for International Cancer Control) tumor-node-metastasis (TNM) classification of malignant tumors, demonstrated that serum exosome lysyl oxidase-like 2 (LOXL2) levels were significantly higher in stage I/II HNSCC patients than in healthy volunteers and stage III HNSCC patients. Here, LOXL2 is linked to head and neck squamous cell carcinoma.