Three transgender military veterans may have developed cancer from taking sex reassignment drugs, a report has revealed.
All of the patients were born male but were identified as female and had recently been prescribed the hormone estrogen to make them more feminine.
Each of them had several risk factors that increase their chances of developing thyroid cancer, including smoking, obesity and radiation exposure.
But doctors who treated them said it “is conceivable” that their hormone therapy played a role based on previous research linking estrogen to tumor growth.
Doctors are now calling for transgender people to be warned about the cancer risks of gender-affirming medications.
A report published earlier this year detailed the cases of three transgender military veterans who were diagnosed with thyroid cancer after receiving hormone therapy (file image)
The number of military personnel diagnosed with gender dysphoria has increased from 1,892 in 2020 to 3,700 in 2024, according to data from the Defense Health Agency.
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The report was published earlier this year in the journal Endocrine and metabolic science by experts from the University of California Davis.
They wrote that while gender-affirming hormone therapy (GAHT) with estrogen ‘is a cornerstone of treatment for transgender women…thyroid cancer has been associated with estrogen.
“Physicians should be aware of this and discuss it with transgender women (in the context of limited data on thyroid cancer in this population) to eliminate health disparities.”
Experts suggested that the estrogen in gender-affirming medications may have caused malignant cells to grow in the thyroid, which could lead to cancerous tumors or benign masses that turn cancerous.
According to data from the Department of Defense, the number of transgender members of the US military has doubled from 1,800 to 3,700 since 2020.
This is less than one in 100 of total active duty military personnel in the US.
The Williams Institute at UCLA estimates that 15,500 transgender people serve in the US military as a whole.
And Defense Health Agency figures show that in the last three years, $17.5 million of taxpayer money was spent on psychotherapy for trans service people and $1.5 million went on medication hormonal.
Another $7.6 million financed gender affirmation surgeriesincluding facial adjustments to make a recruit more masculine or feminine, and the removal or creation of breasts and genitals.
The report comes as thyroid cancer is expected to affect 44,000 patients this year and kill 2,100.
It’s also one of the fastest-growing cancers in the United States, and experts attribute it to environmental factors such as exposure to “forever chemicals.”
All three patients in the case report were diagnosed with papillary thyroid cancer, which accounts for approximately eight in 10 cases of thyroid cancer.
When detected early, more than nine out of 10 patients survive after five years. This figure drops to about half when the cancer spreads to other areas.
The first patient was 49 years old when he was diagnosed with cancer in 2002, five years after starting hormone replacement therapy.
In addition to being on estrogen therapy, the patient also had “significant radiation exposure” due to helping clean up the Chernobyl nuclear disaster.
The patient was also obese with a BMI of 32.
They had their thyroid removed in 2003 and then went into remission. They discontinued estrogen therapy in 2008 and underwent a breast reduction two years later.
The patient resumed hormone replacement therapy in 2016.
The second patient was diagnosed with papillary thyroid cancer at age 55 in 2011. They had started hormone therapy three years earlier and had vaginoplasty, a surgery to create a vagina and vulva, in 2009.
They had no family history or history of risk factors such as smoking or radiation exposure. However, they were obese with a BMI of 30.
Doctors noted that at the time of diagnosis, the patient was taking an “unknown total dose” of estrogen pills.
The patient had his thyroid removed two months after his diagnosis and had no recurrence. It is unclear whether they continued gender-affirming care.
One of the most famous examples of transgender military personnel is Admiral Rachel Levine, a four-star officer who was sworn in as an admiral in the Public Health Services Commissioned Corps in 2021 (pictured here in 2022).
Since 2020, $17.5 million has been spent on psychotherapy, $1.5 million on hormone therapy and $7.6 million on gender-affirming surgeries, according to Department of Defense data provided to DailyMail.com.
A recent analysis of more than 400 cases showed the most serious side effects and reactions experienced by patients undergoing hormonal therapies.
The third patient was 64 years old when he was diagnosed with thyroid cancer in 2017, just three months after starting estrogen therapy.
However, doctors had found a benign thyroid tumor five years earlier. They noted that because the nodule was benign until hormone therapy began, it is possible that the treatment turned cancerous.
Although the patient was not overweight and had no family history of the disease, he smoked more than 50 packs of cigarettes a year, which increased the risk of thyroid cancer.
The patient did not undergo surgery due to heart disease and chronic obstructive pulmonary disease (COPD) caused by smoking.
In 2021, the patient died of atherosclerotic cardiovascular disease, a heart condition caused by plaque buildup inside the arteries, making it difficult for blood to flow throughout the body.
The researchers noted that gender-affirming care was the only common denominator among the three patients, as they all otherwise had different risk factors for thyroid cancer.
However, they also wrote that the evidence suggesting that estrogen might increase the risk of thyroid cancer is mixed and is mostly done in animals.
Dr. Hiba Tariq Basheer, assistant clinical professor of health sciences at UC Davis, said in a Press release: “We are being cautious with our findings, but more research is needed to determine the role of sex-affirming hormone therapy with estrogen and thyroid cancer.”
