Once again, the false equivalence between bioidentical progesterone and synthetic progestins (which medicine has been promoting for decades) is on full display. The study below found that chronic use of several of the most commonly prescribed synthetic progestins increases risk of developing intracranial meningioma. That tumor is rare and usually does not cause serious issues when forming in the spinal column/cord area. However it can become dangerous and even life threatening when forming inside the head, and that type is exactly what the study found elevated risk for from the use of the synthetic progestins. On the flip side, several studies have demonstrated reduced risk of meningioma when using biodentical progesterone. The findings of the study are likely explainable by the fact that estrogen is a known cause/promoter of meningiomas and many/most synthetic progestins are actually estrogenic (as I posted about years ago). In contrast, bioidentical progesterone has purely anti-estrogenic effects by being both an estrogen receptor antagonist as well as an aromatase inhibitor.
https://www.bmj.com/content/384/bmj-2023-078078
“…Noémie Roland, M.D., M.P.H., from the EPI-PHARE Scientific Interest Group in Saint-Denis, France, and colleagues conducted a national case-control study involving 108,366 women overall to examine the risk for intracranial meningioma associated with use of selected progestogens. Cases included 18,061 women living in France who had intracranial surgery for meningioma between Jan. 1, 2009, and Dec. 31, 2018; each case was matched to five controls (90,305 controls). The researchers found that the risk for meningioma was increased with use of medrogestone (0.2 percent among cases versus 0.1 percent among controls; odds ratio, 3.49), medroxyprogesterone acetate (injectable; 0.05 versus 0.01 percent; odds ratio 5.55), and promegestone (0.5 versus 0.2 percent; odds ratio, 2.39). The excess risk was driven by use for one year or longer. No excess risk for intracranial meningioma was seen for progesterone, dydrogesterone, or levonorgestrel intrauterine systems. Due to the small number of people receiving dienogest or hydroxyprogesterone, no conclusions could be drawn.”
