Too Much Estrogen Can Raise Men’s Risk of Breast Cancer

Estrogen is often called the “female hormone,” but everyone needs it — no matter their sex. Though men usually have lower levels of estrogen, it’s still crucial for their health.

Estrogen is especially important for male sexual and reproductive health. For example, it’s needed for the normal development and function of sex organs like the testes and prostate. The hormone also plays a role in sex drive, erections, and sperm production.

Men benefit from estrogen in other ways, too. It helps increase muscle and reduce fat, strengthens bones, and protects the heart. Estrogen also affects mood, skin, and more.

Sometimes men can have too much, or too little, estrogen. Too much estrogen can hurt sexual health by causing infertility, erectile dysfunction, and gynecomastia (enlargement of breast tissue). Research suggests that it may also increase the risk of male breast cancer.

Androgens are a group of sex hormones that includes testosterone. They are the most common type of sex hormone in men. The body naturally converts a small amount of androgens into estrogen. 

Estrogen levels in men can vary based on their age and health. But, most experts agree that the normal male range for the main form of estrogen, called estradiol, is about 10 pg/mL (picograms, or one trillionth of a gram, per milliliter of blood) to 50 pg/mL. In comparison, normal estradiol in premenopausal women can be as high as 300 pg/mL.

Doctors don’t test estrogen levels in men unless they have a reason to think they might be too high or too low. If you think your estrogen levels may be outside of the normal range, talk to your healthcare provider about testing. Avoid using at-home estrogen testing kits because they aren’t very accurate.

A few health conditions can cause high estrogen in men. These include diabetes, overactive thyroid (hyperthyroidism), and liver scarring (cirrhosis). Tumors in the adrenal glands, which sit on the top of the kidneys and make hormones, and tumors in the testes can also cause high estrogen. Obesity can raise estrogen levels, but some research suggests that it does not raise them above the normal range.

A rare cause of high estrogen is aromatase excess syndrome. In this condition, the body makes too much of an enzyme (called aromatase) that converts testosterone into estrogen. A genetic mutation causes this syndrome. It can be passed down from a parent, or the mutation can be from a new genetic change in a person with no family history.

Aromatase excess syndrome can occur in both people who are assigned female at birth (and have XX chromosomes) and those assigned male at birth (and have XY chromosomes), though it’s more common in the latter. When someone with XY chromosomes has aromatase excess syndrome, they are considered intersex because they have typical male sex traits but also grow breasts. They may grow up to identify as a man or as a different gender identity.

There are three main symptoms of high estrogen in adult males: infertility, erectile dysfunction, and gynecomastia.

Just because you have these symptoms doesn’t mean you have high estrogen. These symptoms can also be caused by aging, low testosterone, other health conditions, or drugs. 

Symptoms of high estrogen may look different in growing kids with aromatase excess syndrome. Kids with XY chromosomes who have this condition may have gynecomastia, an early growth spurt, and shorter adult height.

It’s important to note that high estrogen in adult males is different from transgender women taking estrogen as gender-affirming hormone therapy. Trans women who take estrogen and testosterone blockers generally have estrogen and testosterone levels close to the normal female range. Men with high estrogen are still nowhere near the female range. High estrogen in males does not cause the same degree of effects that trans women have when taking estrogen, such as less body hair, less muscle, and more body fat around the hips and butt. High estrogen in males also has nothing to do with gender identity.

Few studies have looked at the potential health effects of high estrogen in males, but research suggests it may raise the risk of male breast cancer. In a 2015 study, researchers found that men with the highest estrogen levels were about 2.5 times more likely to develop breast cancer than men with the lowest estrogen levels.

Male breast cancer is rare, but it is possible because all men have at least a small amount of breast tissue. It is more common in older men. Because obesity raises estrogen levels, maintaining a healthy weight can help prevent male breast cancer. Drinking alcohol also increases estrogen levels. So, limiting your alcohol may help prevent the disease.

Some studies suggest that high estrogen may alter the immune system, such as by increasing inflammation. Chronic inflammation is linked to many health issues, such as heart disease, diabetes, and cancer.

One study found that high estrogen in males is linked to depression.

More research is needed to confirm these links, and to look into whether high estrogen in males increases the risk of other health issues.

There are several treatments for high estrogen. If a tumor is the cause, you may need surgery, chemotherapy, or radiation to get rid of it. If another health condition — such as diabetes, hyperthyroidism, or liver scarring — is the cause, treating that underlying condition should help bring estrogen levels into a normal range.

While receiving treatment for the underlying condition, you may also be prescribed medicines called selective estrogen receptor modulators (SERMs) or aromatase inhibitors. These medicines lower estrogen levels and are sometimes used to treat breast cancer in women. SERMs block the effect of estrogen on some tissues. Aromatase inhibitors stop the body from converting testosterone to estrogen.

Sometimes healthcare providers will prescribe treatments to help with the symptoms of high estrogen. Gynecomastia sometimes goes away on its own, but other times it may be treated with estrogens blockers or surgery, and estrogen blockers like SERMs may help treat male infertility caused by low sperm count. To treat erectile dysfunction, doctors may prescribe medications like Viagra that increase blood flow to the penis.