Progestin VS Natural Progesterone

In a 2005 review of clinical studies comparing synthetic progestins to natural progesterone, Campagnoli and coauthors (J Steriod Biochem Mol Biol 96, 95-108) concluded that: "The balance of the in vivo evidence is that progesterone does not have a cancer-promoting effect on breast tissue... We therefore suggest that when HRT is indicated, preparations containing progesterone and not a synthetic progestin should be used, according to a sequential or cyclic-combined regimen. In this way the risk of endometrial cancer is minimized without increasing the risk of Breast Cancer."

In another 2005 clinical trial comparing synthetic progestins to the natural progesterone, Fournier and coworkers (Int J Cancer 114, 448-454) found that: "The risk was significantly greater than p0.001 with HRT containing synthetic progestins than with HRT containing micronized progesterone, the relative risk being 1.4 and 0.9, respectively." Yes, that’s right; progesterone users had a lower risk.

Cordially,

Helen Pensanti M.D.