Abstract: To observe the effect of interference treatment and mechanism in early stage with selective COX2 inhibitor for experimental hepatocarcinoma and angiogenises in rats. Methods: The rats were divided into two groups: inducing group (n=12) and interferential group (n=40). The rats in inducing group only drank 0.01% The experiment showed that the selective COX2 inhibitor intervened and slowed the process of rat experimental liver cancer. The interferential effect in the early carcinogenesis mainly based on the suppression of tumor growth and induction of apoptosis by inhibiting COX2 expression, and the effect on tumor angiogenesis in early carcinogenesis has not been shown . diethylnitrosamine (DEN) water, whereas the rats in interferential group not only drank DEN water but also received selective COX2 inhibitor Rofecoxib 30?mg/kg daily. The rats were killed in batches at the 6th and the 9th week of the experiment separately. Meanwhile, the cyclooxygenase2(COX2), microvessel density（MVD）, Bcl2 and proliferating cell nuclear antigen (PCNA) of the livers were detected by immunohistochemistry. Results: The grade of pathological change in interferential group was lighter than that in inducing group. The expressions of COX2 and Bcl2 at the 6th and the 9th, PCNA at the 9th week of the experiment in interferential group was far lower than those in inducing group(P＜0.01, P＜0.05; P＜0.05, P＜0.01 and P＜0.05 separately) whereas the value of MVD in two groups was low and the difference was not significant at the experiment group(P＞0.05).

Key words: Liver neoplasms, Cyclooxygenase, Cyclooxygenase2 inhibitor, Rats