Breast cancer risk in transgender people receiving hormone treatment: nationwide cohort study in the Netherlands

Abstract

ObjectiveTo investigate the incidence and characteristics of breast cancer in transgender people in the Netherlands compared with the general Dutch population.DesignRetrospective, nationwide cohort study.SettingSpecialised tertiary gender clinic in Amsterdam, the Netherlands.Participants2260 adult trans women (male sex assigned at birth, female gender identity) and 1229 adult trans men (female sex assigned at birth, male gender identity) who received gender affirming hormone treatment.Main outcome measuresIncidence and characteristics (eg, histology, hormone receptor status) of breast cancer in transgender people.ResultsThe total person time in this cohort was 33 991 years for trans women and 14 883 years for trans men. In the 2260 trans women in the cohort, 15 cases of invasive breast cancer were identified (median duration of hormone treatment 18 years, range 7-37 years). This was 46-fold higher than in cisgender men (standardised incidence ratio 46.7, 95% confidence interval 27.2 to 75.4) but lower than in cisgender women (0.3, 0.2 to 0.4). Most tumours were of ductal origin and oestrogen and progesterone receptor positive, and 8.3% were human epidermal growth factor 2 (HER2) positive. In 1229 trans men, four cases of invasive breast cancer were identified (median duration of hormone treatment 15 years, range 2-17 years). This was lower than expected compared with cisgender women (standardised incidence ratio 0.2, 95% confidence interval 0.1 to 0.5).ConclusionsThis study showed an increased risk of breast cancer in trans women compared with cisgender men, and a lower risk in trans men compared with cisgender women. In trans women, the risk of breast cancer increased during a relatively short duration of hormone treatment and the characteristics of the breast cancer resembled a more female pattern. These results suggest that breast cancer screening guidelines for cisgender people are sufficient for transgender people using hormone treatment.

Breast cancers, mammary stem cells, and cancer stem cells, characteristics, and hypotheses

“…Albeit studies remain scarce, the same discrepancy is observed for transgender male to female, where breast cancer is usually diagnosed at a younger age 51.5-year old while the incidence of breast cancer is increased by 46-fold when compared to male [13 , 14] . The transition from male to female relies on antiandrogens and estrogen therapies, which increase the risk of breast cancer [14] .…”

Troubling blind spots in understanding cancer risks among transgender patients

“…The research included 2260 transgender women and 1229 transgender men receiving gender‐affirming hormones at the VU University Medical Center Amsterdam's gender clinic. The study concluded that the breast cancer risk for the transgender women, who received mostly antiandrogen and estrogen therapy, was approximately 47‐fold higher than the risk for Dutch cisgender men, but more than 3‐fold lower than the risk for Dutch cisgender women . The risk for transgender men receiving testosterone therapy likewise was much higher than that for cisgender men but approximately 5‐fold lower than the risk for cisgender women.…”

Provider Recommendations Are Associated with Cancer Screening of Transgender and Gender-Nonconforming People: A Cross-Sectional Urban Survey

“…5 Breast cancer risks for transgender women with longitudinal exposure to estrogen are reported to be greater than cisgender women but less than cisgender men. 6 Cervical cancer risks for transgender men are sometimes erroneously assumed by providers to be lower than for cisgender women. 7 Cancers are most treatable when cancer screening is guideline driven.…”