Background: Trans women can receive gender-affirming hormone treatment (HT) to induce feminization including breast growth. Previous studies showed modest breast development induced by HT. However, measurement methods used resulted probably in an underestimation of the growth. Furthermore, patient related outcome measures were not measured in previous studies.
Objectives: To prospectively examine breast growth in cubic centimeter (cc) and cup-sizes in transwomen during HT evaluated with 3D imaging and to study whether clinical or laboratory parameters modified the observed development. Furthermore, we investigated the satisfaction of trans women with the gained breast development.
Methods: All Dutch speaking adult trans women starting HT from February 2017 until December 2017 were eligible for participation in this study. Several clinical and laboratory parameters were collected every 3 months during outpatient clinic visits. 3D images of the thorax using the Vectra scanner were collected every 3 months as well and all participants filled out two questionnaires at time of the 3D imaging (i.e. perceived self-esteem and a questionnaire about satisfaction with the gained breast growth). Mixed model analyses were performed to study breast growth during the first year of HT. Analyses were adjusted for age, weight change, serum hormone levels (i.e. LH, estradiol, and testosterone) and were stratified for estrogen administration route (oral versus transdermal).
Results: In the current analyses, 52 trans women who completed the first year of HT were included. The median age was 25.5 (inter quartile range (IQR) 21-38, range 18-60). Breast development increased with 112 cc in the left breast and 120 cc in the right breast to 174 cc and 184 cc, respectively. This resulted in 94% of the transwomen in a cup-size <AAA cup.
Conclusions: These first analyses of the collected data showed little breast development during the first year of HT. Upcoming analyses will also include clinical, laboratory and satisfaction data.