SERPINE1 and head and neck squamous cell carcinoma: High tumor PAI-1 levels (z-score >2) are constantly prognostic for poor disease outcomes and shorter disease-free survival in various malignancies [138,139,140,141], such as node-negative breast cancer, ovarian serous carcinoma, glioblastoma, renal clear cell carcinoma and gastric cancer as well as head and neck squamous cell carcinoma (HNSCC) [142,143,144,145,146].