A novel aromatase inhibitor, vorozole, shows antitumor activity and a decrease of tissue insulin-like growth factor-I level in 7, 12-dimethylbenz[a]anthracene-induced rat mammary tumors.

: Effects of vorozole, a potent and specific non-steroidal aromatase inhibitor, were evaluated on female Sprague-Dawley (SD) rats with 7, 12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors. Vorozole at a dose of 0.25, 1.0 and 4.0 mg/kg was orally administered once a day for 28 consecutive days. A significant regression in tumor size was observed in each treated group at 1, 2, 3 and 4 weeks after the start of treatment compared with control group. Tissue insulin-like growth factor I (IGF-I) in the DMBA-induced tumors in each treated group significantly decreased in a dose-dependent fashion compared with control group. These results show the mechanism of vorozole in DMBA-induced rat mammary tumors.