Transgender people undergo prolonged hormone treatment, which may be associated with an increased risk of breast cancer. This study aims to evaluate the incidence of breast cancer in trans men and women who received gender-affirming hormone treatment.
This is a retrospective, nationwide, cohort study conducted in a specialized tertiary gender clinic in Amsterdam, the Netherlands. The study included a total of 2,260 adult trans women (female gender identity) and trans men (male gender identity) who received gender-affirming hormone treatment. The primary outcome of the study is the incidence and characteristics of breast cancer in transgender people.
Out of 2,260 trans women in the study, 15 cases of invasive breast cancer were identified. Most of the tumors were of ductal origin and progesterone and estrogen receptor-positive, and 8.3% were human epidermal growth factor-positive. In 1,229 trans men, 4 cases of invasive breast cancer were identified. It was also found that the prevalence of breast cancer in trans women was 46-fold higher than in cisgender men, and the prevalence of breast cancer in trans men was lower than in cisgender women.
The research concluded that trans women receiving gender-affirming hormone therapy were at a higher risk of invasive breast cancer than cisgender men and trans men.