A retrospective review of the use of bicalutamide in transfeminine youth; a single center experience.

Androgen blockers are an essential part of gender affirming care in post-pubertal transfeminine patients. Bicalutamide is a highly potent androgen receptor blocker that is used primarily in adults. We aimed to review our experience with the use of bicalutamide in transgender adolescents who were assigned male at birth. A retrospective review of medical records of transfeminine patients treated with bicalutamide during an 8-year period was conducted. Forty patients, aged 15.5 ± 1.55 years were identified, of whom 21 (53%) were started on bicalutamide alone and 19 were started concurrently on estrogen. In patients on bicalutamide alone, 90.4% reported breast development at their first follow up visit, which occurred at a median of 7.1 months. Patients were treated for 29.4 ± 18.2 months. No episodes of liver toxicity related to bicalutamide were seen. Although these results are preliminary, bicalutamide appears to be a safe option for androgen blockade in transgender girls.