Ray Peat said:The studies that show cancer prevention by progesterone have, over the years, failed to resonate in the medical culture. The confusion created by classifying the antiprogestational, carcinogenic synthetics as "progestins" is largely responsible for the failure to understand the protective nature of progesterone.
If the evidence showing that progesterone prevents or cures cancer could be weighed against the evidence purporting to show that it is carcinogenic, I think it would be clear that something like a cultural-commercial misogyny has been at work. The novelty of the newer misogyny is that it is so often led, or at least figureheaded by women.
Estrogen, progesterone, and cancer: Conflicts of interest in regulation and product promotion.