PTGS2 and gastric cancer: ω-6 enhances the metastatic potential energy of gastric cancer cells by being converted into PGE2 that promotes tumor growth after binding to COX-2; ω-3 can inhibit the activity of COX-2 and reduce the production of PGE2 on the one hand, thereby inhibiting the metastatic potential energy of gastric cancer; on the other hand, ω-3 can compete with ω-6 to bind to COX-1 to produce PGE3 so as to inhibit the metastatic potential energy of gastric cancer.