AIM: To clarify the clinicopathologic significance of COX-2 expression in human colorectal cancer. METHODS: A total of 128 surgically resected colorectal cancer specimens were immunohistochemically analyzed with the use of anti-COX-2, anti-VEGF and anti-MMP-2 antibodies. The relationship between the cyclooxygenase-2 expression in primary lesions of colorectal cancer and clinicopathoiogic parameters was evaluated by chi-square test. RESULTS: Among 128 cases of colorectal cancer, 87 (67.9%) were positive for cyclooxygenase-2. The expression of cyclooxygenase-2 was significantly correlated with the depth of invasion, stage of disease, and metastasis (lymph node and liver). Patients in T3-T4, stages Ⅲ-Ⅳand with metastasis had much higher expression of cyclooxygenase-2 than ones in T1-T2, stages Ⅰ-Ⅱ and without metastasis (P<0.05). Among 45 cases of colorectal cancer with lymph node metastasis, the COX-2-positive rate was 86.7% (39/45) for primary lesions and diffuse cytoplasmic staining for COX-2 protein was detected in cancer cells in 100% of metastatic lesions of the lymph nodes. VEGF expression was detected in 49 tumors (38.3%), and VEGF expression was closely correlated with COX-2 expression. The positive expression rate of VEGF (81.6%) in the cyclooxygenase-2-positive group was higher than that in the cyclooxygenase-2-negative group (18.4%, P<0.05). MMP-2 expression was detected in 88 tumors (68.8%), and MMP-2 expression was closely correlated with COX-2 expression. The positive expression rate of MMP-2 (79.6%) in the positive COX-2 group was higher than that in the negative COX-2 group (20.4%, P<0.05). CONCLUSION: Cyclooxygenase-2 may be associated with tumor progression by modulating the angiogenesis and cancer cell motility and invasive potential in colorectal cancer and it can be used as a possible biomarker. AIM: To clarify the clinicopathologic significance of COX-2 expression in human colorectal cancer. METHODS: A total of 128 surgically resected colorectal cancer specimens were immunohistochemically analyzed with the use of anti-COX-2, anti-VEGF and anti-MMP- 2 The relationship between the cyclooxygenase-2 expression in primary lesions of colorectal cancer and clinicopathoiogic parameters was evaluated by chi-square test. RESULTS: Among 128 cases of colorectal cancer, 87 (67.9%) were positive for cyclooxygenase-2. The expression of cyclooxygenase-2 was significantly correlated with the depth of invasion, stage of disease, and metastasis (lymph node and liver). Patients in T3-T4, stages III-IV and with metastasis had much higher expression of cyclooxygenase-2 than ones in T1 -T2, stages Ⅰ-Ⅱ and without metastasis (P <0.05). Among 45 cases of colorectal cancer with lymph node metastasis, the COX-2-positive rate was 86.7% (39/45) for primary lesions and diffuse cytoplasmic sta ining for COX-2 protein was detected in cancer cells in 100% of metastatic lesions of the lymph nodes. VEGF expression was detected in 49 tumors (38.3%), and VEGF expression was detected in cancer cells in 100% of metastatic lesions of the lymph nodes of VEGF (81.6%) in the cyclooxygenase-2-positive group was higher than that in the cyclooxygenase-2-negative group (18.4%, P <0.05) The positive expression rate of MMP-2 (79.6%) in the positive COX-2 group was higher than that in the negative COX-2 group (20.4%, P <0.05 CONCLUSION: Cyclooxygenase-2 may be associated with tumor progression by modulating the angiogenesis and cancer cell motility and invasive potential in colorectal cancer and it can be used as a possible biomarker.