Can Estrogen Increase Your Risk of Breast Cancer

High amounts of estrogen or prolonged exposure throughout your life may increase your risk of breast cancer. But there are steps you can take to lower your overall risk.
Estrogen itself isn’t always dangerous and is, in fact, a necessary component in human development. However, in some cases, increased estrogen exposure over your lifetime may increase your risk of developing breast cancer.

In this article, we take a closer look at estrogen, including when and why it may increase your risk of developing breast cancer and steps you can take to lower your risk.
What role does estrogen play in the human body?

Estrogen is a type of female reproductive hormone primarily produced by the ovaries, skin, and fat tissues. It’s also responsible for helping the human body develop female sexual characteristics. In particular, estrogen plays a role in:
• the development of breast, vulva, and vaginal tissues
• assisting in pregnancy and contraception
• bone density and development
• cholesterol regulation

How does estrogen increase your risk of breast cancer?
In some cases, doctors may prescribe estrogen for:
• pregnancy prevention
• moderate acne
• female hypogonadism
• advanced prostate cancer
• menopause symptom relief

Estrogen is a physiological necessity for people assigned male or female at birth. However, it may be harmful in large amounts and may even increase the risk of breast cancer development.
Hormone replacement therapy (HRT)
People assigned female at birth who are postmenopausal and take hormone replacement therapy (HRT), also called menopausal hormone therapy, may especially be at risk.

HRT is sometimes prescribed to help alleviate symptoms of menopause, such as hot flashes, changes in mood, and night sweats, especially if these symptoms interfere with your quality of life. However, the pros and cons of HRT must be weighed carefully because of the risk of breast cancer.
According to the National Cancer InstituteTrusted Source, estrogen-only HRT may increase your risk of breast cancer, and this risk does not decrease if you stop taking the medication. On the other hand, combination HRT with estrogen-progestin also increases your risk, but this may go down slightly after you stop taking it.

Other estrogen-related factors
While HRT may increase your risk of breast cancer, there are other factors that can increase your estrogen exposure and subsequent cancer risk. These include:
• taking oral contraceptives (although more studiesTrusted Source are needed)
• diethylstilbestrol use during pregnancy (prevalent between 1940 and 1971Trusted Source)
• early menstruation
• late onset of menopause
• not having given birth
• first birth at an older age

What are the non-estrogen-related risk factors of breast cancer?
Aside from estrogen exposure, other factors may increase your lifetime risk of developing breast cancer.
While having any of these risk factors doesn’t mean you’ll automatically develop cancer, you may consider discussing these with a doctor or healthcare professional to help lower your risk overall.
Overweight and obesity
Lack of physical activity
Drinking alcohol
Not having children or breastfeeding

Other possible risk factors
• a high fat diet
• environmental chemicals such as plastics and pesticides
• shifts in melatonin and other hormones because of nightshift work
• secondhand smoke exposure
• exposure to radiation, such as that of chest X-rays (especially before the age of 20), because it can increase breast cancer risk for women with inherited changes in the BRCA1 and BRCA2 genes

What can you do to prevent breast cancer?
While there’s no single method of cancer prevention, there are steps you can take to lower your risk of developing breast cancer. The ACSTrusted Source recommends that you:
• achieve and keep a moderate weight
• limit (or avoid) alcohol
• get at least 150 to 300 minutes of moderate exercise per week
• talk with a doctor about genetic counseling if breast cancer runs in your family
• consider preventive surgeries (such as breast or ovary removal) or estrogen-blocking medications as recommended by a doctor if you’re deemed high risk