HPRT1 and head and neck squamous cell carcinoma: Importantly, Kaplan-Meier survival curves showed that patients with high expression of HPRT1 had worse overall survival (OS) and disease-free survival (DFS) compared to those patients with low expression of HPRT1 (Figure 1C), indicating that HPRT1 is a potential prognostic index in HNSCC.