Frequency and outcomes of benign breast biopsies in trans women: A nationwide cohort study.

No literature is available on the benign versus malignant breast lesion ratio in trans women (male sex assigned at birth, female gender identity). As hormone treatment in trans women results in breast tissue histologically comparable with cis (non-trans) women, breast pathology may be expected. Previously, an increased breast cancer risk compared with cis men have been observed. We aimed to investigate the frequency and outcomes of breast biopsies in trans women. Therefore, we retrospectively examined the medical files of 2616 trans women. To gain data on breast lesions, we linked our cohort to a national pathology database. In this study we found that 126 people (5%) had one or more breast biopsies (n = 139). Of these, 21 trans women had a breast biopsy before the start of hormone treatment, and 53 after the start of hormone treatment. Breast biopsies were performed predominantly because of abnormalities during physical examination (37%, n = 51/139 biopsies), or because of capsular formation or contraction (28%, n = 16/57 biopsies) in trans women with breast implants. The most common breast lesions after the start of hormone treatment were fibroadenomas (n = 20), breast cancer (n = 6), fibrosis (n = 5), cysts (n = 4), and infections (n = 4). The benign versus malignant breast biopsy ratio was 88:12, which is comparable to the ratio in cis women (90:10). This study shows breast lesions in a limited number of trans women. Since the indications and outcomes of biopsies in trans women were similar to those in cis women, it seems reasonable to follow breast care guidelines as developed for cis women.