Trial reportThe Journal of clinical endocrinology and metabolism2025
Effect of Spironolactone and Cyproterone Acetate on Breast Growth in Transgender People: A Randomized Clinical Trial.
Trial report in The Journal of clinical endocrinology and metabolism, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
4 citing papers in PubMed.
- Effect of Spironolactone and Cyproterone Acetate on Breast Growth in Transgender People: A Randomized Clinical Trial.The Journal of clinical endocrinology and metabolism · 2025Trial
- Effect of anti-androgens on body composition in transgender people: Secondary analysis of a randomized clinical trial.International journal of transgender health · 2026Article
- Plasma proteome adaptations during feminizing gender-affirming hormone therapy.Nature medicine · 2026Article
- Approach to prolactin monitoring and hyperprolactinaemia in transgender and gender-diverse individuals undergoing gender affirming hormone therapy.Frontiers in endocrinology · 2025Article
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Authors and funding
7 authors.
Funding
Abstract
contextTransgender people with sex recorded male at birth desiring feminization commonly use cyproterone acetate or spironolactone as antiandrogens with estradiol, but the optimal antiandrogen is unclear.
objectiveWe aimed to assess the effect of antiandrogens on breast development. We hypothesized this would be greater in those treated with cyproterone acetate than spironolactone due to more potent androgen receptor antagonism and suppression of serum total testosterone concentrations.
methodsA randomized clinical trial was conducted between 2020-2022 at an outpatient endocrinology clinic. Transgender people aged 18+ years old commencing feminizing gender affirming hormone therapy were included. The intervention was standardized estradiol therapy plus either spironolactone 100 mg daily or cyproterone acetate 12.5 mg daily for 6 months. The primary outcome was breast development as measured by the breast-chest distance. Secondary outcomes included estimated breast volume, suppression of serum total testosterone concentration <2 nmol/L, and Gender Preoccupation and Stability Questionnaire (GPSQ).
resultsSixty-three people (median age 25 years) were enrolled, randomized, and included in intention to treat analysis (cyproterone acetate n = 32, spironolactone n = 31). At 6 months, there was no between-group difference in breast-chest distance (mean difference 0.27 cm, 95% CI -0.82 to 1.35, P = .6) or estimated breast volume (mean difference 17.26 mL, 95% CI -16.94 to 51.47, P = .3). Cyproterone acetate was more likely to suppress serum testosterone concentration to <2 nmol/L (odds ratio 9.01, 95% CI 1.83 to 4.44, P = .008). Changes in GPSQ were similar between groups.
conclusionAntiandrogen choice should be based on clinician and patient preference with consideration of side effects. Further research is needed to optimize breast development in transgender people.
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