PTGS2 and cancer: Based on these observations, COX-2 inhibitors can prevent the growth of human cancer cells by reducing the levels of COX-2 and PGE2 in tumors and enhancing the activity of chemotherapy drugs.50 However, celecoxib in combination with TKIs did not evidently improve OS (including OS-6 and OS-12; this may be due to the EGFR mutational status in patients with advanced NSCLC, which was undefined in our study.