Sex and Breast Cancer Risk
Being a cisgender woman is one of the biggest risk factors for developing breast cancer. There are about 297,790 new cases of invasive breast cancer and 55,720 cases of non-invasive breast cancer this year in American women.
While cisgender men do develop breast cancer, less than 1% of all new breast cancer cases happen in men. Approximately 2,800 cases of breast cancer will be diagnosed in American men this year.
Very little research has investigated how breast cancer risk differs for transgender people in comparison to cisgender women and men. One of the largest studies on this topic, conducted in the Netherlands, found that:
the breast cancer risk of trans women was 46-fold higher than that of cis men — though still much lower than the risk for cisgender women
the breast cancer risk for trans men was five times lower compared to cis women
But this is just one study; more research is needed. Either way, risk may be lower for trans men and non-binary people who were assigned female at birth (afab) if they have had chest masculinization surgery. And risk for transgender women and non-binary people who were assigned male at birth (amab) may be higher than that of cisgender men (but lower than that of cisgender women) if they are receiving feminizing hormone therapy.
The biggest reasons for the difference in breast cancer rates between cisgender men and women relate to hormonal stimulation of highly responsive and vulnerable breast cells in women, particularly during the extra-sensitive period of breast development.
Women's breast development takes 3 to 4 years and is usually complete by age 14. It's uncommon for men's breasts to fully form (most of the male breasts you see are fat, not formed glands). Once fully formed, breast cells are very immature and highly active until a woman's first full-term pregnancy. While they are immature, a woman's breast cells are very responsive to estrogen and other hormones, including hormone disruptors in the environment. Men's breast cells, meanwhile, are inactive, and most men have extremely low levels of estrogen.
Steps you can take
There are lifestyle choices you can make to reduce your estrogen exposure and reduce your risk of breast cancer:
never smoking (or quitting if you do smoke)
These are just a few of the steps you can take. Review the other breast cancer risk factors for more options.
— Last updated on July 19, 2024 at 6:18 PM