PTGS2 and head and neck squamous cell carcinoma: On the other hand, such a link between cancer stage and COX-2 immunoexpression was not statistically significant in some studies that examined patient samples from OSCC [39,41,51,55,66,67,78], TSCC [37,76], LSCC [69], HNSCC [74,75], NPC [52,70,71,82], and glottic cancer [89].