Abstract: Objective: To investigate the expression of cyclooxygenase-2 (COX-2) and vascular endothelial growth factor-C (VEGF-C) in human rectal adenocarcinoma． Methods: COX-2 and VEGF-C expressions were determined in 40 cases of rectal adenocarcinoma and 40 cases of normal rectal mucous membrane by the immunohistochemical PV-8000 two-step staining method． Lymphanigogenesis was evaluated by immunohistochemical staining with the specific antibody, VEGFR-3． Results: Expression rate of COX-2 and VEGF-C was 62.5%(25／40) and 65.0%(26／40)， respectively in 40 rectal adenocarcinoma specimens． VEGFR3 was positive in 21 cases（21/40， 52.5%）indicating lymphangiogenesis in the tumors．Expression of COX-2 was significantly correlated with that of VEGF-C， tumor lymphangiogenesis and lymphatic metastasis and serosa invasion（P＜0.05)， however, it did not correlate with the tumor size， location and histological typing（P＜0.05）． Conclusions: In rectal adenocarcinoma， expression of COX-2 is significantly associated with VEGF-C， lymphangiogenesis and lymphatic metastasis． COX-2 may up-regulate the expression of VEGF-C， which induces lymphangiogenesis and contributes to lymphatic metastasis．

Key words: Rectal neoplasms, Cyclooxygenase-2, Lymphangiogenesis, Lymph node metastasis