Context: Cyproterone acetate (CPA) is an androgen receptor blocker often used for testosterone suppression as a part of gender-affirming hormonal treatment (GAHT) in transgender women. In recent years, more concerns have been raised towards an increased risk of meningioma development, linked to CPA use in higher doses (25 mg or more per day).
Objectives: To determine if lower doses of CPA are equally effective in maintaining adequate testosterone suppression and feminization without increasing unwanted effects, measured by patient-reported outcomes.
Design: prospective cohort study
Methods: This longitudinal study was conducted at a specialized tertiary gender identity clinic in Ghent, Belgium. The participants were trans women (n= 72) taking a low (defined as 10 or 12.5 mg) or a high (defined as 25 or 50 mg) daily dose of CPA in combination with estrogens. Validated questionnaires assessing body image (Body Image Scale) and hormonal symptoms (Menopause Rating Scale) were used to measure patient-reported outcomes.
Results: After three months of GAHT, all but one participant had a suppressed serum testosterone, irrespective of CPA dose. Satisfaction with breast development was non-inferior in the low-dose CPA group compared to the high-dose CPA group (P= 0.078) after one year of GAHT. Hormonal symptoms evaluated through MRS after three (P= 0.676) or 12 months (P= 0.684) did not differ significantly between the low-dose and the high-dose CPA group. Sub-analysis for participants who decreased the dose of CPA from 25 to 12.5 mg during the first year of hormonal treatment showed an increase of hormonal complaints (evaluated by MRS), though not statistically significant.
Conclusion: Lower doses of CPA (10 or 12.5 mg per day) are equally effective in suppressing serum testosterone while maintaining an adequate feminization, measured by breast development satisfaction (Body Image Scale), in the absence of additional hormonal complaints after 3 or 12 months of GAHT.