Chemopreventive effect of tamoxifen combined with celecoxib on DMBA-induced breast cancer in rats

BACKGROUND & OBJECTIVE: Breast cancer can be prevented partly by tamoxifen. Cyclooxygenase-2 (COX-2) is expressed in many kinds of tumors, and correlated to the occurrence and progress of tumors. This study was to evaluate the chemopreventive effect of tamoxifen combined with celecoxib, a COX-2 selective inhibitor, on 7,12-dimethylbenz anthracene (DMBA)-induced breast cancer in rats. METHODS: DMBA was irrigated into the stomach of SD female rats to build breast cancer model. The rats were divided into 4 groups: control group, tamoxifen group, celecoxib group, and combination group; each group contained 30 rats. Tumor occurrence, latency period, number and volume of breast cancer were observed. RESULTS: The tumor occurrence rates in tamoxifen group (48.15%, 13/27) and celecoxib group (50.00%, 14/28) were lower than that in control group (85.71%, 24/28), and higher than that in combination group (21.43%, 6/28). The latency periods of tamoxifen group [(97.54+/-1.85) days] and celecoxib group [(96.79+/-2.89) days] were longer than that of control group [(89.50+/-5.99) days], and shorter than that of combination group [(103.67+/-3.39) days]. The tumor numbers of tamoxifen group (1.77+/-0.73) and celecoxib group (1.71+/-0.61) were less than that of control group (3.50+/-1.62), and more than that of combination group (1.17+/-0.42). The tumor volumes of tamoxifen group [(1.78+/-0.71) cm(3)] and celecoxib group [(2.05+/-1.04) cm(3)] were smaller than that of control group [(6.42+/-3.96) cm(3)], and larger than that of combination group [(0.71+/-0.96) cm(3)]. All differences were significant (P<0.05, respectively). CONCLUSION: Celecoxib and tamoxifen could effectively prevent the occurrence of DMBA-induced breast cancer in rats; the combination of them has better chemopreventive effect.