AIM:Cyclooxygenase-2 (COX-2) is one of the rate-limitingenzymes in metabolism of arachidonic acid,and COX-2inhibitors demonstrate preventive effects on cancer,especially on colorectal cancer.The underlying mechanismremains unclear.The aim of this study was to illustratethe relationship between angiogenesis and COX-2 incarcinogenesis of colorectal cancer.METHODS:One hundred and seventy patients withcolorectal cancer were enrolled in our study from January1993 to September 2001 in School of Oncology,PekingUniversity.COX-2 and VEGF expression were detected withthe immunohistochemistry (IHC) technique.IHC assayswere carried out with the aid of tissue microarray (TMA)procedure.Specimens from 35 of these patients wereexamined with reverse transcriptase PCR (RT-PCR).RESULTS:COX-2 and VEGF expressions were stronger incolorectal cancer than those in the corresponding normaltissues,at both protein and mRNA levels.One hundredpatients were eligible for analysis after IHC assay of COX-2 and VEGF.The positive rate of VEGF was much higher inCOX-2 positive group (47/85) than in COX-2 negative group(X~2=4.181,P=0.041).The result was further verified bythe result of RT-PCR (X~2=8.517,P=0.003).Correlationcoefficient was 0.409 after Spearman correlation analysis(P=0.015).CONCLUSION:COX-2 may be involved in the course oftumor angiogenesis of colorectal cancer and acts throughVEGF. AIM: Cyclooxygenase-2 (COX-2) is one of the rate-limitingenzymes in metabolism of arachidonic acid, and COX-2 inhibitors to demonstrate preventive effects on cancer, especially on colorectal cancer. The underlying mechanism is unclear. The aim of this study was to illustrate the relationship between angiogenesis and COX-2 incarcinogenesis of colorectal cancer. METHODS: One hundred and seventy patients with colorectal cancer were enrolled in our study from January 1993 to September 2001 in School of Oncology, Peking University. COX-2 and VEGF expression were detected with the immunohistochemistry IHC) technique. IHC assays were carried out with the aid of tissue microarray (TMA) procedure. Specimens from 35 of these patients wereexamined with reverse transcriptase PCR (RT-PCR) .RESULTS: COX-2 and VEGF expressions were stronger incolorectal cancer than those in the corresponding normal tissues, at both protein and mRNA levels. One hundredpatients were eligible for analysis after IHC assay of COX-2 and VEGF.Th e positive rate of VEGF was much higher in COX-2 positive group (47/85) than in COX-2 negative group (X ~ 2 = 4.181, P = 0.041) .The result was further verified by the result of RT-PCR ~ 2 = 8.517, P = 0.003) .Correlationcoefficient was 0.409 after Spearman correlation analysis (P = 0.015) .CONCLUSION: COX-2 may be involved in the course of tumor angiogenesis of colorectal cancer and through through VEGF.