RESUMO
New selective cyclooxygenase-2 inhibitors offer the benefit of cancer protection with less gastrointestinal toxicity associated with nonselective nonsteroidal anti-inflammatory drugs (NSAIDs). We hypothesize that MF tricyclic and sulindac can retard all stages of tumor formation in nude mice. In a blinded placebo controlled study, 3 types of experiments were performed: 1) 2.5 x 10(6) cells were injected into 2 flanks of nude mice subcutaneously, as a model for in situ cancer (n = 192); 2) 1 x 10(6) cells were injected into the cecum of mice as a model for in situ colorectal cancer (n = 78) and 3) 0.5 x 10(6) cells were implanted into the splenic subcapsule to establish a colorectal cancer liver metastasis model (n = 78). The animals were fed with standard chow containing either placebo, MF tricyclic (67 mg/kg of chow) or sulindac (150 mg/kg of chow). Mice that were given MF tricyclic or sulindac, at clinical anti-inflammatory plasma concentrations, were significantly more tumor free and had significantly smaller primary tumors and fewer metastases, as compared to mice that consumed placebo. The mortality and the latency period were significantly better in the treatment groups. These findings suggest that selective COX-2 inhibitors may serve as an adjunct to standard therapy in colorectal cancer.