SULF2 and head and neck squamous cell carcinoma: Although the HNSCC serum samples showed a higher mean concentration of SULF2 (n = 28, mean = 849 pg/ml serum, SD = 491) compared to control samples (n = 35, mean = 732 pg/ml serum, SD = 412), we did not observe a significant difference (p-value = 0.56) in the SULF2 concentration.