UCSD Radiation Medicine and Applied Sciences La Jolla, CA
P. Riviere1,2, K. M. Morgan3,4, L. N. Deshler5, M. D. Tibbs6, E. M. Qiao3,6, J. Anger7, A. Salmasi7, D. C. Marshall8, P. Sanghvi9, and B. S. Rose3,6; 1University of California San Diego Department of Radiation Medicine and Applied Sciences, La Jolla, CA, 2VA San Diego, San Diego, CA, 3VA San Diego Health Care System, La Jolla, CA, 4UCSD Health, Department of Radiation Medicine and Applied Sciences, La Jolla, CA, 5UCSD Center for Health Equity, Education, and Research, La Jolla, CA, 6Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, CA, 7UCSD Department of Urology, La Jolla, CA, 8Department of Radiation Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, 9Department of Radiation Medicine and Applied Sciences, UC San Diego School of Medicine, La Jolla, CA
Purpose/Objective(s): There are limited data on the effects of gender affirming hormone therapy on prostate specific antigen (PSA) values in transgender or non-binary individuals (TGNB) born with prostate glands. Additionally, the relative incidence of prostate cancer in TGNB individuals compared to cisgender men is poorly characterized. This study hypothesized that various gender affirming hormone therapies would significantly reduce PSA, and possibly result in lower incidence of prostate cancer either due to biological effect or from reduced detection with PSA suppression. Materials/
Methods: This was a multicenter, nationwide cohort study of individuals receiving care in the VA Healthcare system. For analyses comparing TGNB individuals to cisgender men, TGNB patients were matched to cisgender controls by year of birth. To account for repeated testing of PSA within patients as well as matching between cohorts, linear mixed effects modeling was employed. We studied separately the effects of gender affirming hormone therapies using gonadotropin-releasing hormone agonist/antagonists (GnRH containing regimens) and non-GnRH containing regimens. We quantified incidence of prostate cancer as new cases per 1000 patient-years, measuring exposure from time of age 50 to last follow up or death. Results: Our cohort included 1,024 self-identified TGNB individuals assigned male at birth who received PSA testing in the VA Healthcare System. Use of non-GnRH hormone therapy was associated with a 1.30 ng/mL lower PSA (95% confidence interval (CI) 1.14-1.46, p < 0.001) and GnRH hormone therapy was associated with a 1.08 ng/mL lower PSA (95% CI 0.60-1.55, p < 0.001) in matched analysis with cisgender men. Within the TGNB cohort, there were 450 individuals who had undergone PSA testing both before and after initiation of hormone therapy. For these individuals, initiation of non-GnRH therapy resulted in a 0.49 ng/mL decrease (95% CI 0.35-0.62, p<0.001) and initiation of GnRH hormone therapy resulted in a 0.73 ng/mL decrease (95% CI 0.43-1.02, p<0.001) from a pre-hormone therapy median PSA baseline of 0.70ng/mL. TGNB individuals developed prostate cancer at a rate of 1.79 per 1,000 patient-years compared to 4.02 per 1,000 patient-years in cisgender individuals. Conclusion: TGNB individuals undergoing gender affirming hormone therapies experience decreases in PSA and are less likely to be diagnosed with prostate cancer than matched cisgender individuals. It is not clear if the lower incidence of prostate cancer is the result of hormonal chemoprevention or ascertainment bias from suppression of PSA. Future work should establish if a lower PSA threshold for biopsy should be used for TGNB individuals receiving gender affirming hormone therapy who elect to undergo prostate cancer screening.
