TIMP1 and oropharynx squamous cell carcinoma: In HPV-negative squamous cell oropharyngeal carcinoma patients, high serum level of matrix metalloproteinase inhibitor (TIMP-1) is associated with poor OS and DFS, suggesting that high serum level of TIMP-1 is associated with poor prognosis in HPV-negative squamous cell oropharyngeal carcinoma patients [32].