Summary
Researchers used records from the Amsterdam gender clinic, which treats over 95% of Dutch transgender patients, linked to the national record of cancer diagnoses. They counted breast cancers in about 3,500 people on cross-sex hormones. Trans women got breast cancer far more often than men normally do (about 46 times), but still less often than women. Their tumours looked like the typical hormone-sensitive breast cancers seen in women. This suggests estrogen, and possibly the testosterone-blocking drug cyproterone acetate, shifts risk toward the female pattern. Trans men had a lower risk than women, likely helped by having had their breasts removed. The authors concluded the overall risk is low and normal screening is enough. With only 15 and 4 cases, missing data on major risk factors, and comparisons with the general population, the numbers are rough.
Key findings
- تابعت الدراسة 2,260 امرأة متحولة و1,229 رجلاً متحولاً على العلاج الهرموني، بما يعادل نحو 34,000 و15,000 سنة متابعة.
- أصيبت النساء المتحولات بـ 15 سرطان ثدي بعد 18 سنة معتادة على الهرمونات (من 7 إلى 37 سنة)، في سن 50 عادة.
- كان سرطان الثدي أشيع بنحو 46 مرة لدى النساء المتحولات منه لدى الرجال (على الأرجح بين 27 و75 مرة)، لكنه أقل شيوعاً بنحو الثلث فقط منه لدى النساء.
- كانت معظم الأورام لدى النساء المتحولات من النوع الحساس للهرمونات (83% يغذيها الإستروجين و67% البروجسترون)، مثل تلك التي تُرى عادة لدى النساء.
- أصيب الرجال المتحولون بـ 4 سرطانات ثدي، نحو خُمس المعدل لدى النساء لكن 59 ضعف المعدل لدى الرجال؛ وحدثت ثلاثة بعد سنوات من استئصال الثديين.
- لم يستطع الباحثون مقارنة الأدوية الهرمونية المختلفة، لأن العلاجات تغيرت كثيراً وتناولت معظم النساء المتحولات أسيتات السيبروتيرون.
- خلص المؤلفون إلى أن قواعد فحص الثدي العادية كافية للمتحولين جنسياً على الهرمونات.
Abstract
OBJECTIVE: To investigate the incidence and characteristics of breast cancer in transgender people in the Netherlands compared with the general Dutch population. DESIGN: Retrospective, nationwide cohort study. SETTING: Specialised tertiary gender clinic in Amsterdam, the Netherlands. PARTICIPANTS: 2260 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 MEASURES: Incidence and characteristics (eg, histology, hormone receptor status) of breast cancer in transgender people. RESULTS: The 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). CONCLUSIONS: This 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.
Conclusion
This large nationwide cohort study in the Netherlands showed an increased risk of breast cancer in trans women compared with cisgender men. The risk in trans women is still lower than in Dutch cisgender women and resembles a more female type of breast cancer and hormone receptor status. In trans men, a lower risk compared with Dutch cisgender women was observed. Based on this study, we conclude that the absolute overall risk of breast cancer in transgender people remains low and therefore it seems sufficient for transgender people using hormone treatment to follow screening guidelines as for cisgender people. As the risk of breast cancer in trans women increased during a relatively short duration of hormone treatment, it would be worthwhile for future studies to investigate in more detail the cause of breast cancer in transgender people receiving hormone treatment.