According to a research letter published in the Journal of the American Medical Association, prostate cancer is not so rare among transgender women. Prior to this work, the entire medical literature on prostate cancer in transgender women consisted of about ten case reports. This had led many to believe that prostate cancer in transgender women was rare. The new research, which describes the first large case series of transgender women with prostate cancer, proves otherwise. However, the rates are lower than expected based on previous estimates of prostate cancer incidence in cisgender male patients.
Dr Farnoosh Nik-Ahd, of the University of California (San Francisco) and colleagues, characterised prostate cancer in transgender women. The analysis included 449 prostate cancer patients and transgender identity codes in the electronic health records of the US Department of Veterans Affairs health care system (from 2000 to 2022).
The researchers found that 155 patients (35%, an estimated 14 cases per year) were transgender women with prostate cancer: 116 had never used oestrogen, 17 had used it previously, and 22 were actively using it at the time of diagnosis. Screening detected all prostate cancer diagnoses at a median age of 61 years (88% white) and a median PSA level of 6.8 ng/mL. Among transgender women with confirmed prostate cancer, the median duration of oestrogen use was 32 months for those who had taken oestrogen and those who were taking it. Nearly half were biopsy grade 1 (biopsy severity was categorised according to a scale of 1 to 5, with 5 being the most severe level) and clinical stage T1 (clinical stage severity was categorised according to a scale of T1 to T4, with T4 being the most severe level). Almost all (152 out of 155) had not undergone bilateral orchiectomy.
Among patients who had not previously used oestrogen, biopsy group 1 or 2 was found in 58 of 82 patients, compared to 9 of 16 with previous oestrogen use and 9 of 17 with oestrogen use at diagnosis. Biopsy group grade 4 or 5 was found in 19 of 82 patients who had never used oestrogen, in 4 of 16 who had taken it and in 6 of 17 who were taking it at diagnosis.
The number of cancers found in transgender women was lower than in cisgender (non-transgender) patients. Furthermore, while about 28% of cisgender male prostate cancer patients were black, only 8% of transgender women with prostate cancer were black.
The researchers could not reach formal scientific conclusions because the number of patients was too small. They suggested that the lack of PSA testing in transgender women could help explain the lower rates of prostate cancer diagnosis.
The authors also suggest that the lower rates of diagnosis among transgender women of colour could be due to a reluctance to identify as transgender with their doctors, who therefore do not screen them. One problem that transgender women face is that it is not entirely clear which PSA levels should be monitored, as oestrogen therapy can lower PSA levels.
In cisgender men, traditionally PSA levels below 4 were perceived to be safe. Transgender patients on gender-confirming hormone therapy have an even drastic decrease in PSA levels. The authors state that they do not yet have data to determine what the cut-off value should be for PSA in transgender women, but speculate that some of these cancers are currently ignored because the cut-off value used is too high.
The researchers hope that this study will stimulate health professionals and patients to consider the possibility of this disease. They conclude by saying that transgender women and their health care providers should not neglect prostate cancer screening.
According to the researchers, when a transgender woman enters a doctor's office, the doctor should remember to consider screening her for prostate cancer, even among patients who have had gender-confirming surgery, because the prostate is usually not removed.
Nik-Ahd F, De Hoedt A, Butler C, et al. Prostate Cancer in Transgender Women in the Veterans Affairs Health System, 2000-2022. JAMA. Published online April 29, 2023. doi:10.1001/jama.2023.6028