Further, because the use of aspirin reduces the risk of death from all cancers including colorectal cancer, lung cancer, and esophageal cancer [19] and high expression of EP2 in tumor lesions have a positive correlation with poor outcome in some cancers [20, 21], a selective EP2 antagonist can also be a strong candidate as a therapeutic drug to treat a variety of cancers. This evidence concerns the gene PTGER2 and lung cancer.