The methylation positivity rates of SHOX2, RASSF1A, and PTGER4 genes in cancer tissues of LC patients were 48.00%, 32.00%, and 64.00%, respectively, which were significantly higher than those in paracancerous tissues, which were 16.00%, 4.0%, and 14.00%, respectively (P < 0.05). This evidence concerns the gene PTGER4 and cancer.