Iris de Nie

116 C H A P T E R 7 Table 1. Characteristics of study cohort (n=3,026) Characteristics n Median (IQR) unless stated otherwise Age at time of start HT, years 3,026 29 (22-41) % history of cryptorchidism 35 1% Serum testosterone concentration at initiation of GAHT, nmol/L 844 18.0 (12.0-23.0) Serum estradiol concentration at initiation of GAHT, pmol/L 840 86 (68-109) Serum testosterone concentration during GAHT, nmol/L 1,714 1.0 (0.6-1.3) Serum estradiol concentration during GAHT, pmol/L 1,756 181 (110-296) % bilateral orchiectomy 1,914 63% Follow-up time, years 3,026 2.3 (1.6-3.7) Total follow-up time, years 3,026 11,223 In total, three cases of testicular cancer were observed in the study cohort. Age at time of diagnosis of the three trans women with testicular cancer ranged from the second to the fourth decade of life. All three trans women were Caucasian, had no medical history for oncological diseases, and their family history was negative for testicular cancer. One person started treatment during adolescence,while the other two started GAHT in adulthood. Used anti-androgenic treatment involved tripterolin, cyproterone acetate, and spironolactone, resulting in serum testosterone levels below 2 nmol/L. Types of used estrogens included estradiol injections, estradiol patches, and estradiol valerate, resulting in mean serum estradiol concentrations between 150 and 300 pmol/L. Estrogens were used for a duration of 1 to 3 years prior to diagnosis. Histology showed non-seminoma (mature teratoma (95%), embryonal carcinoma ( < 5%) and yolk sac tumor ( < 5%)) in one case, pure seminoma grown into the rete testis in the second case, and a seminoma with syncytiotrophoblast cells in the third case. Tumor diameters ranged from 0.9 to 6.8 centimeters. None of the trans women had metastasis and all remained clinically stable after treatment. Two of the previously mentioned testicular cancer cases were discovered due to symptoms of a painless scrotal mass. Based on age-specific incidence rates in cis men, we expected 2.4 cases of testicular cancer in our cohort. This resulted in a SIR of 0.8 with a 95% CI of 0.1 to 2.8. Subgroup analysis of 2,731 trans women who initiated GAHT when 18 years or older, showed two testicular cancer cases although 2.2 cases would have been expected, resulting in a SIR of 0.9 (95% CI 0.2-3.0). In the subgroup of 523 trans women with a follow-up time of at least 5 years (median 8.9 years, IQR 6.4-13.9, total 5,870 years), no testicular cancer cases were observed, although 1.2 cases would have been expected based on the age-specific incidence rates in cis men. Of the 1,914 trans women who underwent bilateral orchiectomy, histopathological analysis of the resected specimens was performed in 722 trans women. Within this group, histopathological analysis showed testicular cancer in one case (0.1% of orchiectomy specimens obtained during GAS).