Thyroid Cancer Prevalence, Risk Exposure, and Clinical Features Among Transgender Female Veterans

Purpose Transgender women experience higher-than-average rates of multiple medical conditions. Thyroid cancer occurs more frequently in those assigned female at birth than in those assigned male at birth. We sought to characterize thyroid cancer among transgender female veterans.Methods We reviewed charts of veterans who were (1) seen in Veterans Affairs clinics across the United States from July 2017 to December 2022, (2) had an International Classification of Diseases, revision 10, diagnosis code for thyroid cancer, and (3) had an International Classification of Diseases, revision 10, diagnosis code for gender dysphoria or were assigned male at birth and ever had a prescription for estrogens. Charts of cisgender veterans were also reviewed for comparison.Results Compared with calculated estimates of 0.641% (95% CI, 0.572-0.724) among cisgender females and 0.187% (95% CI, 0.156-0.219) among cisgender males, the measured prevalence among transgender female veterans was 0.341% (34/9988). Average age at thyroid cancer diagnosis in this population was 53.8 (+/- SEM 2.61) years. A total of 32.3% (11/34) of these patients had extrathyroidal disease at diagnosis.Discussion To our knowledge, this study represents the first report of thyroid cancer prevalence among transgender women in the United States. Risk exposure among all transgender veterans including further assessment of the possible contributions of obesity, smoking, and gender-affirming hormone therapy are important future analyses.