Gender-affirming hormone therapy and the risk of sex hormone-dependent tumours in transgender individuals—A systematic review

Abstract

Background: Cancers are a leading cause of death worldwide, and transgender individuals are no exception. The effects of gender-affirming hormone therapy (GAHT) on sex hormone-dependent tumours are unclear. Therefore, this review seeks to determine whether tumour risk in transgender individuals differs from the general population, to guide clinical screening recommendations. Methods: We performed a systematic review based on the PRISMA guidelines. MEDLINE, Embase and PsycINFO databases were searched for studies examining tumour incidence, prevalence or cancer-related mortality in transgender individuals. All English peer-reviewed publications were included if histological type and temporal relation to GAHT were reported. Case reports were included if there were ≥2 cases of the same histological type. Results: The search strategy identified 307 studies. Excluding those that did not meet inclusion criteria, 43 studies (7 cohort studies, 2 cross-sectional studies and 34 case reports) were reviewed. Retrospective cohort studies suggest no increase in risk of tumour development in transgender individuals receiving GAHT compared to the general population. Notably, the mean ages of cohorts were young and were treated with GAHT for insufficient durations to assess tumour risk. Case reports raise potential associations between high-dose oestradiol and anti-androgen therapy with prolactinoma and meningioma, respectively. Conclusions: Further longitudinal studies are required to assess the risk of GAHT and hormone-dependent tumour development. Until further evidence is available, tumour screening should be based on guidelines for the general population and the presence of organs in transgender individuals rather than gender identity or hormonal therapy status.