Univariate analysis shows that high SULF2 expression is significantly associated with poor PFI of HNSCC patients (HR = 1.653, p = 0.001, Figure 2B) and shows a weaker trend for SULF1 (HR = 1.408, p = 0.075, Figure 2A). Here, SULF1 is linked to head and neck squamous cell carcinoma.