While in lung and colon carcinogenesis the role of prostaglandin E2 receptors is well established by many researches, a small number of studies have assessed their involvement in HNSCC and described that EP3 and EP4 receptors were expressed in cancer cell lines but Very weak EP1 and EP2 receptors expression was noticed [30]. This evidence concerns the gene PTGER3 and head and neck squamous cell carcinoma.