However, and despite the aforementioned evidence, several studies found no correlation between COX-2 and DFS, including studies on NPC [71,72,73,84], OSCC [41,45], HNSCC [81,85], TSCC [67,88], glottic cancer [89], and LSCC [100]. The gene discussed is PTGS2; the disease is nasopharyngeal carcinoma.