The expression of COX-2 is upregulated in many cancers. COX-2 overexpression has been associated with increased microvascular density, and VEGF protein expression in head and neck Squamous Cell Carcinomas and is a poor prognostic indicator in this entity as well. The overexpression of COX-2 along with increased angiogenesis and GLUT-1 expression is significantly associated with gallbladder carcinomas. Furthermore the product of COX-2, PGH2 is converted by prostaglandin E2 synthase into PGE2, which in turn can stimulate cancer progression. Consequently inhibiting COX-2 may have benefit in the prevention and treatment of these types of cancer. The mutant allele PTGS2 5939C carriers among the Han Chinese population have been shown to have a higher risk of gastric cancer. In addition, a connection was found between Helicobacter pylori infection and the presence of the 5939C allele. COX-2 overexpression has also been suggested as a poor prognostic indicator in Carcinomas of the Colon, Breast, Pancreas, and Adenocarcinomas of the Lung.