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Endocrine Abstracts (2018) 56 P955 | DOI: 10.1530/endoabs.56.P955

1Department of Endocrinology and Center of Expertise on Gender Dysphoria, VU University Medical Center, Amsterdam, Netherlands; 2Department of Clinical Genetics, VU University Medical Center, Amsterdam, Netherlands; 3Department of Clinical Genetics, Antoni van Leeuwenhoek Hospital, Amsterdam, Netherlands; 4Department of Pathology, VU University Medical Center, Amsterdam, Netherlands; 5Department of Oncology, VU University Medical Center, Amsterdam, Netherlands.


Background: Transpersons can receive gender affirming hormone therapy (HT) to induce physical changes. Little is known about the effect of HT on breast cancer (BC) risk.

Objectives: To study the prevalence and characteristics of BC in transpersons with HT and to compare this prevalence with the general Dutch male and female population.

Methods: Adult transpersons who were seen after 1991 and started HT in the VUmc were included. This cohort was linked in August 2017 to the nationwide PALGA database, which registers histopathology and cytopathology in the Netherlands. Information about the date of diagnosis, type of BC, and hormone receptor status was retrieved.

Results: 2,567 transwomen (median age at start of HT 30 years, inter quartile range (IQR) 23-41) and 1,324 transmen (median age at start of HT 23 years, IQR 19-31) were included with a follow-up time of 22,576 and 10,109 person-years, respectively. In transwomen, 18 BC cases were identified, while 72 BC cases (based on Dutch female reference rates) and 0.4 cases (based on Dutch male reference rates) were expected. In transmen, 4 cases were identified, while 21 and 0.1 cases were expected, respectively. Three transmen were diagnosed with BC several years after mastectomy. The median age at diagnosis was 51 years (range 30-73) in transwomen and 47 years (range 35-59) in transmen, which is lower than the average 61 years in the female reference population. Median number of years of HT before BC diagnosis was 222 months (range 79-490) in transwomen and 176 months (range 23-199) in transmen. In both groups, the most prevalent type of BC was ductal carcinoma, with 67% and 75%, respectively. In transwomen, 80% of the tumors were estrogen receptor positive (ER+), 67% progesterone receptor positive (PR+) and 7% human epidermal growth factor receptor-2 positive (HER2/neu+). In transmen, 50% was ER+, 50% PR+, and 25% HER2/neu+.

Conclusions: This study showed an increased risk of BC compared with the Dutch male reference population. Although the age at diagnosis was lower, the risk of BC in transpersons is still lower than in the Dutch female reference population.

Volume 56

20th European Congress of Endocrinology

Barcelona, Spain
19 May 2018 - 22 May 2018

European Society of Endocrinology 

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