title: Relationship between COX-2 expression and clinicopathological features of colorectal cancers.
abstract: BACKGROUND
  Cyclo-oxgenase 2 (COX-2) is involved in prostaglandin synthesis in central nervous system, and it also plays a role in human carcinogenesis. Our purpose of this study is to investigate the COX-2 expression in different development stages of colorectal cancer, and to discuss the relationship between the gene expression and clinicopathological features of the cancer.
  
  
  METHODS
  COX-2 expression was examined by immunohistochemical staining in 76 surgical specimens of colorectal cancer (44 of advanced stage and 32 of early stage), thirty-three adenomas and 18 normal colonic mucosal tissues taken by endoscopic biopsy. Kaplan-Meier survival curves and Cox proportional hazards regression were used to evaluate the relation of COX-2 to prognosis.
  
  
  RESULTS
  COX-2 expression, divided into 4 grades from "-" to "+++", is respectively 83.3%, 16.7%, 0% and 0% in normal colonic mucosal tissues; 12.1%, 42.4%, 36.4% and 9.1% in adenomas; 6.3%, 28.1%, 46.9% and 18.7% in early colorectal cancers (ECCs), and 6.8%, 20.5%, 18.2% and 54.5% in advanced colorectal cancers (CRCs). The differences in COX-2 expression between advanced CRCs and early colorectal cancers (ECCs) as well as between the advanced CRCs and adenomas were statistically significant (P < 0.01); but there was no significant difference between ECCs and adenomas. Kaplan-Meier survival analysis showed a significant difference in the survival curves between low high COX-2 groups (P < 0.05). Cox proportional hazards regression showed that COX-2 expression was related to poorer long-term outcome with a hazard ratio of 2.665 unadjusted for other variables (P < 0.05), and COX-2 expression was an independent risk factor of poor prognosis.
  
  
  CONCLUSIONS
  COX-2 expression is gradually up-regulated in the development from normal epithelium to adenomas and from ECCs to advanced CRCs. Alhough the COX-2 protein can not be regarded as a tumor marker to diagnose CRCs early, COX-2 expression can be regarded as an independent risk factor of poor prognosis for postoperative patients with advanced CRCs.
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510120, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhan
authors.forename: Jian-ping
authors.initials: JP
authors.lastname: Liu
authors.forename: Zhao-hua
authors.initials: ZH
authors.lastname: Zhu
authors.forename: He-rui
authors.initials: HR
authors.lastname: Yao
authors.forename: Chun-yan
authors.initials: CY
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000401:mortality / Q000473:pathology; D051546:Cyclooxygenase 2; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D011379:Prognosis; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis*; D015996:Survival Rate
chemical_list: D007527:Isoenzymes; D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases