Iris de Nie

126 C H A P T E R 8 Table 1. Characteristics of study cohort. Total cohort (n=2,281) Age at time of study (years) 50 (37-59) Age at start of hormonal treatment (years) 31 (23-41) Body Mass Index (kg/m²) 22.7 (20.5-25.6)ˆ % Caucasian ethnicity 96.7 (n=1579) ˜ % (former) smokers 39.0 (n=890) % orchiectomy 68.9 (n=1572) Follow-up time (years) 14 (7-24) Total follow-up time (years) 37,117 Data available for: ˆ1,357 and ˜1,633 people of cohort. Values are medians (interquartile ranges) unless stated otherwise. Six people were diagnosed with prostate cancer, after median 17 years (range 10-24) of hormone treatment. The six trans women with prostate cancer had started hormone treatment at a median age of 47 years (range 38-58). Four of these six individuals had undergone orchiectomy, median 11 years (range 2-14) prior to the prostate cancer diagnosis. The median age at time of diagnosis was 64 years (range 53-77). Histology reports of the six prostate cancer cases in our cohort showed adenocarcinoma in all cases. Gleason scores, the recommended prostate cancer grading system, were available for five trans women. 140 In all cases, there was at least one biopsy with a Gleason score of 7 or higher, suggesting a tumor with intermediate risk or higher. With a median of 18 ng/ mL (range 5-1,722), serum levels of prostate specific antigen (PSA) were elevated at time of diagnosis in all cases. Based on age-specific incidence rates, the number of expected prostate cancer cases in our cohort was 30. Since only six cases were observed in our cohort (16.2 cases per 100,000 years), the prostate cancer risk was considerably lower compared to Dutch cis males (SIR 0.20, 95%CI 0.08-0.42). This preventive effect holds in a subgroup analysis of trans women who underwent orchiectomy as part of their gender-affirming treatment (SIR 0.17, 95%CI 0.05-0.40, Table 2).