PTGS2 and head and neck squamous cell carcinoma: However, a correlation between COX-2 immunoexpression and T-stage was not found to be statistically significant in some studies about OSCC [25,51,55,66,67] LSCC [16,68,69], HPSCC [24], MEC [70], NPC [71,72,73], HNSCC [74,75], and tongue squamous cell carcinoma (TSCC) [76].