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trans nonbinary chest with scars from top surgery

Illustration by Marta Pucci

Cycle A-Z

What trans men and nonbinary people need to know about breast cancer

by Laurie Ray, Science Writer at Clue
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Top things to know

  • It seems to be rare, but trans men and AFAB (assigned female at birth) nonbinary people can still develop breast cancer even after top surgery, and/or while taking testosterone
  • We don’t know how gender-affirming testosterone therapy affects a person’s risk of developing breast cancer
  • Binding does not increase the risk for breast cancer
  • People who have had a mastectomy or top surgery (removal of the breasts) likely have a lower risk for breast cancer

Breast cancer risk

All people (regardless of their sex assigned at birth) have breast tissue and could potentially get breast cancer, but the risk is much higher in people who were AFAB (assigned female at birth). Studies focused on cisgender (non transgender) people have found that, over a lifetime, 1 in 8 women and 1 in 800 men will be diagnosed with breast cancer (1). The risk for breast cancer among trans men and AFAB nonbinary people is not well understood. Those who are not taking testosterone and who have not had any gender-affirming surgeries such as a mastectomy or top surgery (removal of the breasts), or an oophorectomy (removal of the ovaries) have the same risk for developing breast cancer as cisgender women.

Much of what we know about trans men and breast cancer is based on case reports (a detailed report of the diagnosis, treatment, and follow-up of an individual, typically used for rare occurrences). Because these reports are based on individual people, they may not be generalizable to the entire population and don’t allow us to understand the frequency of breast cancer among trans men. Since the early 2000s, fewer than 20 cases of breast cancer in trans men have been reported in the medical literature (2-9). Prior to being diagnosed, almost two thirds had taken testosterone, a quarter had had a mastectomy, and more than a third had done neither.

For transgender men, and AFAB nonbinary or genderqueer people, the risk of breast cancer will likely depend on many factors, such as:

  • Age
  • Personal and family history of cancer
  • Genetics
  • History of childbirth and breastfeeding
  • Hormone user
  • Whether they have had any gender-affirming surgeries

Does testosterone therapy affect the risk of breast cancer?

Testosterone use does cause changes to breast tissue, but more research is needed to understand its impact on breast cancer risk. One study conducted in the Netherlands aimed to determine the rate of breast cancer among trans men taking testosterone. The researchers looked at more than four decades of medical records of 795 trans men who were all taking testosterone for an average of 20 years (2). They found only one case of breast cancer in this group.

The rate of breast cancer among trans men in this study was estimated to be much lower than the rate of breast cancer among cisgender women and similar to the rate among cisgender men in the Dutch population (2).

Some researchers have raised concern that taking testosterone could put people at risk for breast cancer because of the young age at which several trans men on testosterone have been diagnosed (2). Among cisgender women, it is uncommon to be diagnosed with breast cancer before 40 years old, and the average age of diagnosis is 62 years old (1). A quarter of the trans men in the reported cases were taking testosterone and younger than 40 when they were diagnosed (2,4,7,8).

How testosterone can impact breast tissue

The breast tissue of trans men taking testosterone has less glandular tissue (the milk producing part of the breast) and more fibrous connective tissue (10,11). Breast cancer occurs in the glandular breast tissue, so it’s possible that testosterone could be protective against breast cancer by shrinking this type of tissue.

Prolonged exposure to estrogen is believed to be a component of breast cancer development (12). The body can convert testosterone to estrogen in a process called aromatization. There is concern that the converted estrogen could increase the risk for breast cancer (2). Breast tissue also contains receptors for androgens (a group of hormones including testosterone), so abnormal growth (that could turn into cancer) could be stimulated by the testosterone itself (13).

Testosterone and breast cancer risk in non-trans women

More research is needed on whether gender-affirming testosterone therapy increases the risk for breast cancer in trans men and nonbinary people. For now, we have some research on how testosterone affects the risk for breast cancer among non-transgender women.

The research on how testosterone impacts risk for breast cancer in non-trans women has been inconsistent. For women prior to menopause (when periods stop permanently), one study found that those with the highest levels of free testosterone (the active form)—but not total testosterone (the active plus the inactive form)—were more likely to be diagnosed with breast cancer (14). Among postmenopausal women with naturally higher levels of estrogen and testosterone, one study found that those with higher testosterone had an increased risk for breast cancer (15), but another found that higher testosterone levels were not associated with increased risk (16).

It can also be difficult to compare breast cancer risk among people taking testosterone since it is given in different dosages and in different forms depending on its purpose. Studies where postmenopausal women used testosterone patches for the treatment of low sex drive showed that testosterone did not increase risk for breast cancer (17). Another study of both pre- and postmenopausal women who were using testosterone implants for hormone deficiency found that it was protective against breast cancer (18). The testosterone dosages in these studies were likely lower than what a trans man would receive.

Can binding affect someone’s risk of breast cancer?

Many trans men and non-binary individuals bind their chests (the practice of compressing breast tissue for the appearance of a flatter chest) to more accurately reflect their gender identity and improve mental and emotional health. While studies have shown that most people who bind will experience at least one negative physical symptom, such as pain, shortness of breath, or skin infections (19,20), no studies have attributed breast cancer to binding.

There is no reason to believe that binding could cause breast cancer.

Do people who have had a mastectomy have a different risk of breast cancer?

The risk of breast cancer in trans men who have had mastectomy or top surgery is not known (21), but is likely lower than those who have not had surgery. In contrast to a mastectomy done to treat someone with breast cancer where the goal is removal of disease, mastectomy performed for the purposes of gender affirmation has appearance and aesthetics as the goal to promote well-being. For trans men who have mastectomies, some of the glandular tissue (the milk producing parts) of the breast may be left behind (22-24), and it's possible that cancer could form in this tissue.

The risk for breast cancer among trans men or nonbinary individuals after top surgery and taking testosterone is likely lower than the risk for cisgender women and slightly higher than the risk for cisgender men (25).

Symptoms and signs to look out for

While seemingly rare, trans men and nonbinary people can still develop breast cancer even after top surgery, and/or while taking testosterone. It’s important to continue to be aware of changes in this part of your body. Some specific things that should be checked by a healthcare provider include:

  • A new lump, especially if it is larger than 2 cm (0.8 in), feels very hard, and is fixed (can not easily be moved from side to side with fingers) (26)
  • Breast pain that is persistently in one spot, especially if there is also a lump (27)
  • Nipple discharge that is bloody, only from one breast, and comes out spontaneously (without being squeezed) (28)
  • If the skin on the breast has sores, becomes red, thick and firm, or looks like the dimpled skin of an orange (28)

Regular check-ups are key

Routine check-ups and screenings are important for staying healthy. Trans men who have not had a mastectomy, or have only had a breast reduction, may choose (after a discussion with their healthcare provider) to start annual mammograms at 40 years old—the same as the recommendation for cisgender women (21,29,30). Some people may have an increased risk for breast cancer due to genetics or other factors and may need a different frequency or type of screening. Talking to a healthcare provider is a good idea to make sure you are getting the best care for yourself.

There are no clear guidelines about breast cancer screening in trans men or nonbinary people who have had a mastectomy. It is recommended that people who are planning to have a mastectomy should have a mammogram prior to surgery (21). For those who have had a mastectomy, mammograms may not be possible (21,25). It is unclear if annual chest exams done by a healthcare provider are useful or necessary for trans men or nonbinary people who have had a mastectomy.

How to find a trans-friendly healthcare provider

When you need a check-up or have a concern, finding a healthcare provider who is respectful and informed can sometimes be a challenge. About 30% of transgender people have delayed or avoided seeking needed health care due to perceived discrimination (31), and about 15% of transgender people report that they have been refused care because of their gender identity (32).

If there is a local advocacy organization in your area, they may be able to help with finding a healthcare provider who is trans friendly. Check out our guide to finding a trans friendly OB/GYN for more tips.

Whether you’re on testosterone, have had top surgery, or neither, it’s important to see a healthcare provider if you have concerns about your chest or notice any changes.

Download Clue to track your health and changes in your body.

Further resources

If you’re worried about getting a breast check, nervous about going to the doctor, or looking for cancer support groups that are trans-inclusive, here are some organizations that may be able to help:

CancerCare’s LGBT Program
Free, professional support services for the LGBT community affected by cancer, as well as information and additional resources (USA).

Center of Excellence for Transgender Health
Educational resources about trans health, and information about support organizations in the USA.

LGBT Hospice and Palliative Care Network
A directory with links to palliative care providers in the USA and Canada

LGBT best and promising practices throughout the cancer continuum
Information and resources for healthcare providers

LGBT Consortium
Directory of resources and groups in the UK, that can be filtered by service and region.

Action for Trans Health
A network of grassroots organisations who campaign for trans people's voices to be at the heart of decision making about our own healthcare (UK).

TranzWiki
A comprehensive directory of support groups and organisations that assist trans and gender non-conforming individuals, including those who are non-binary and non-gender, as well as their families, in the UK.

Gender Minorities Aotearoa
Support and information for people living in Aotearoa New Zealand, including a list of trans-friendly healthcare providers.

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