Study finds no increased risk of gynecological cancer with testosterone use after five years

Transmasculine and gender-diverse individuals who use testosterone are not at increased risk of gynecological cancer in the first years of hormone therapy. This is evident from large-scale research by Amsterdam UMC, which was published in eClinicalMedicine.

The results provide important insights for health care providers and transmasculine and gender-diverse individuals who are considering starting hormone therapy.

Transmasculine and gender-diverse people are registered as women at birth, but do not feel male, non-binary or otherwise at home within the traditional image of being a woman. Many of them choose to use testosterone: a hormone therapy that induces physical changes that are more in line with their gender identity and/or expression.

Researchers at Amsterdam UMC followed 1,955 young transmasculine and gender-diverse individuals, who used testosterone for an average of five years. They specifically investigated the risk of cancer of the uterus, ovaries, vagina and vulva during testosterone use.

Asra Vestering, researcher at Amsterdam UMC, explains, “We found no increased risk of these cancers compared to women from the general population. None of these cancers were diagnosed in the entire participant group. This is valuable information for both health care providers and transmasculine and gender-diverse people who are considering starting hormone therapy.”

It was also striking that in some of the participants the endometrium was still active, or that signs of ovulation were observed, despite the use of testosterone.

Wouter van Vugt, co-researcher at Amsterdam UMC, explains, “This is not only relevant for long-term health, but also means that despite testosterone use, there is still a chance of pregnancy. That is why good gynecological care and contraceptive care remains essential for this group, even after the start of hormone therapy.”

In recent years, gender registration legislation in the Netherlands has been relaxed, making surgical gender removal no longer a requirement to legally change gender. As a result, more and more transmasculine and gender-diverse people are choosing to start hormone therapy first, without undergoing sex removal surgery (immediately).

Although no definitive conclusions can yet be drawn about the effects of long-term testosterone use, these findings offer reassurance for individuals who have started or want to start testosterone use.

Vestering emphasizes, “This research provides important knowledge for better information and guidance of transmasculine and gender-diverse people. At the same time, follow-up research into the effects of long-term testosterone use remains necessary, so that care can be further tailored to safety and quality of life.”