Specifically, the N-stage was significantly correlated with COX-2 immunoexpression in OSCC [45,51,59,77,78], LSCC [62], HPSCC [24,64], MEC [70], NPC [65,71,79], TSCC [37], OPSCC [80], and HNSCC [52,81]. Here, PTGS2 is linked to head and neck squamous cell carcinoma.