Skin cancer incidence in transgender individuals receiving gender-affirming hormone treatment: a nationwide cohort study in the Netherlands.

Background: Development of skin cancer, in particular melanoma, has been linked to sex hormones. We aimed to determine the incidence of skin cancer in transgender individuals receiving gender-affirming hormone treatment (GAHT).

Methods: In this nationwide retrospective cohort study, clinical information of participants who visited our clinic between (the years) 1972 and 2018 and received GAHT was integrated with national pathology and cancer statistics data in order to assess skin cancer incidence. Standardized incidence ratios (SIRs) were calculated.

Results: The cohort consisted of 2,436 trans women and 1,444 trans men. The median age at the start of GAHT was 31 years (IQR 24-42) in trans women and 24 years (IQR 20-32) in trans men. The median follow-up time for trans women was 8 years (IQR 3-18) with a total follow-up time of 29,152 years and 4 years (IQR 2-12) with a total follow-up time of 12,469 years for trans men. Eight trans women were diagnosed with melanoma (SIR 1.80 [95% CI 0.83-3.41] vs. all men; SIR 1.40 [0.65-2.65] vs. all women), and seven developed squamous cell carcinoma (SIR 0.78 [0.34-1.55] vs. all men; SIR 1.15 [0.50-2.27] vs. all women). Two trans men developed melanoma (SIR 1.05 [0.18-3.47] vs. all men; SIR 0.77 [0.14-2.70] vs. all women).

Conclusions: GAHT did not appear to affect skin cancer incidence in this large cohort of transgender individuals. As skin cancer incidence increases with age and the proportion of elderly subjects is currently limited in this cohort, it will be worthwhile to repeat this analysis in the future.