PTGER4 and lip and oral cavity carcinoma: Furthermore, the groups of high MI were extremely low of 5hmC levels and was correlated with increasing expression of DNMT3A and DNMT3B. To our knowledge, our study is the first to suggest that PTGDR1, PTGER4, PTGIR, and TBXA2R methylation is associated with worse DFS and may be a critical event in hypopharyngeal cancers, laryngeal cancers, oropharyngeal cancers, and oral cancers, respectively.