Natural and Synthetic Progestins Accelerate 7,12-Dimethylbenz[a]Anthracene-Initiated Mammary Tumors and Increase Angiogenesis in Sprague-Dawley Rats

Abstract
Purpose: Synthetic progestins are widely used therapeutically; however, there is controversy regarding their proliferative effects. We used a rat 7,12-dimethylbenz[a]anthracene (DMBA)–induced mammary tumor model to test the hypothesis that progestins increase angiogenesis and as a result decrease the latency period and increase the multiplicity of mammary tumors.