Cyclooxygenase-2 (COX-2) inhibitors are regarded as potentially important in strategies for cancer treatment. however, the precise mechanisms of these anti-inflammatory drugs as anti-cancer therapy are still unknown. In this study, we examined the effect of DFU both in vitro on MCF-7 cell growth, as well as in vivo on tumor growth produced by MCF-7 cell injection in mice. DFU has growth inhibitory effects on tumor growth in mice compared to the control group. We examined the tumor tissues for apoptosis and angiogenesis by immunostaining. Apoptosis was detected only in the treatment group. DFU treatment also resulted in the inhibition of angiogenesis, as well as decreased COX-2 expression. Results of this study suggest that inhibitory effects of DFU might be COX-2 dependent.