Does going off of testosterone (and on estrogen) protect trans women from prostate cancer?

As part of gender affirming (sexual reassigning) medical care, male to female transgender individuals go on a hormonal protocol that includes androgen deprivation and estrogen supplementation. The medical treatments for transitioning from male to female however do not include removal of the prostate gland, as it is considered unnecessary and aggressive surgery. Thus, even though a trans woman may have a female’s external anatomy and a female hormonal profile, she retains a prostate gland and some risk of getting prostate cancer disease. So, how serious is that risk?

In this new study out of the Netherlands, which included data from 2281 trans women, who were followed for 14 years, 6 cases of prostate cancer were identified after a median of 17 years of hormone treatment. The individuals had started their hormone treatment between the ages of 38 and 58 for a median of 11 years before they were diagnosed with prostate cancer. Their median age at diagnosis was 64, which is very close to the median age for men to get diagnosed with prostate cancer.

Based on the age of the trans women in this study, we would expect 30 cases of prostate cancer in a comparable sample of men in general. Thus the hormonal treatments which the trans women received cut their prostate cancer risk to a fifth of what they might have expected, if they have not transitioned to female.

The conclusion is simple and clear: androgen deprivation plus estrogen supplementation lowers the risk of prostate cancer. There are, however, a few other interesting points about this study. Notably, the study supports the view that testosterone contributes to the risk of prostate cancer and, conversely, that supplemental estrogen does not promote prostate cancer.

To read the full paper, see: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7379905/

de Nie I, de Blok CJM, van der Sluis TM, et al. Prostate Cancer Incidence under Androgen Deprivation: Nationwide Cohort Study in Trans Women Receiving Hormone Treatment. J Clin Endocrinol Metab. 2020;105(9):dgaa412.