Disclaimer: I am not a doctor, and this is not medical advice. Do not take any medication without appropriate medical supervision.

Cyproterone acetate (CPA) is a hormonal medication commonly used as an antiandrogen for trans women, as well as in birth control pills and in the treatment of acne, hirsutism, PCOS, precocious puberty, and prostate cancer. While CPA is unapproved in the United States, it is widely used elsewhere as a component of trans women’s hormone therapy.

Rarely, use of CPA has been associated with the growth of meningioma, a usually-benign brain tumor that develops from the membranes covering the brain. The symptoms of meningioma can vary based on its location, and broadly include headaches, muscle weakness, double vision or vision loss, seizures, and memory loss. However, many meningiomas cause no symptoms and may be found incidentally during brain scans (Chamberlain, 2015). About 70% of meningiomas have progesterone receptors (Blitshteyn, Crook, & Jaeckle, 2008), and meningiomas occur about twice as often in those assigned female (Wiemels, Wrensch, & Claus, 2010). CPA has a strongly progestogenic action, suggesting a mechanism by which use of CPA can promote the growth of these tumors.

Cases of meningiomas linked to CPA use have been reported in cis women (Bernat et al., 2015), cis men (Sys & Kestelyn, 2015), and trans women (Gazzeri, Galarza, & Gazzeri, 2007; Cebula et al., 2010; Bergoglio et al., 2013; Knight & McDonald, 2013; Borghei-Razavi et al., 2014; Mancini et al., 2017; Boer et al., 2018). A 2016 study found three cases among 2,810 trans women treated at the Amsterdam Gender Clinic, and all of these meningiomas occurred in women using CPA (Ter Wengel et al., 2016). The authors estimate a prevalence of meningioma in trans women of 126 in 100,000, compared to a prevalence in the general population of 97.5 in 100,000. However, it is noted that the prevalence in trans women may be an underestimate, as many of these tumors are asymptomatic and there is no routine screening for them.

Meningiomas are typically slow-growing and most can be successfully treated with surgery and/or radiation. Additionally, discontinuation of CPA has been associated with the regression of some meningiomas even without invasive treatment. In a case series of 12 cis women with meningioma who were taking CPA, discontinuing this medication led to a reduction in tumor size for 11 and a cessation of tumor growth in the remaining patient, with no recurrences observed after a year (Bernat et al., 2015).

The authors note that development of meningiomas appears to be particularly associated with long-term use of CPA and high doses (50mg/day or greater). While meningioma in trans women is described as “fortunately, rare” (Ter Wengel et al., 2016), given that trans women on CPA typically use doses of 50-100mg/day (Fung, Hellstern-Layefsky & Lega, 2017), those using this medication should be aware of the possibility of developing these tumors and pay attention to any potential symptoms of meningioma. ■