PTGS2 and cancer: The CpG island hypermethylation heralds an increased risk of prostate cancer recurrence (Yegnasubramanian et al., 2004; Bastian et al., 2005; Phé et al., 2010; Moritz et al., 2013), and inhibiting PTGS2 in pancreatic cancer will reverse T-cell exclusion and sensitized tumors to immunotherapy (Markosyan et al., 2019), indicating that PTGS2 has a relationship with the tumor microenvironment (TME) in certain cancer.