PTGS2 and cancer: Su et al (5) found that a higher level of cyclo-oxygenase-2 decreased the survival rate of patients through many mechanisms, such as a corresponding higher level of vascular endothelial growth factor that stimulated the growth and migration of cancer cells (6), a higher lymphatic vessel density that reduced the restriction of cancer cell invasion (7), and enhanced lymph node metastasis that accelerated the metastasis of cancer cells (8).