Does Estrogen Cause Breast Cancer?
Menopause and Breast Cancer Risk
Breast cancer is the most common female cancer worldwide. Many are aware that 1 out of every 8 women in the U.S. will be diagnosed with breast cancer during her lifetime. This statistic means many are touched by breast cancer whether personally or through a loved one. That’s why we need to take breast cancer seriously and know how to be proactive. The main risk factors impacting breast cancer are genetics and lifestyle. We can’t influence our genetics, but our daily choices can make a difference.
Estrogen plays a role in approximately 80% of the most common breast cancer cases. It is thought that how much estrogen one is exposed to over time, and how a person’s cells respond to the hormone, influence their risk for breast cancer. The longer the body is exposed to estrogen throughout life, the greater the risk for estrogen-related breast cancer, which is why most women are diagnosed with breast cancer later in life. If a person starts their menstrual cycle after age 15, the risk decreases because there are fewer years of higher estrogen exposure. If a woman goes through menopause later in life, that means more years of estrogen exposure and possibly increased risk for breast cancer.
While not all breast cancer is linked to estrogen, estrogen positive (ER+) cancers are the most common. More than half (65%) of ER+ breast cancers respond to progesterone, indicating that the balance of hormone levels is important to keeping healthy.
Estrogen is good and we need it!
However, the ratio to other hormones, like progesterone and testosterone, is equally important. More estrogen is needed during the reproductive years; after menopause estrogen levels decline. Higher levels of estrogen (estradiol) after menopause that could increase breast cancer risk usually come from the environment and one’s lifestyle, in women with no family history of estrogen-related breast cancer.
Although it is common to gain weight after menopause, women should attempt to maintain a healthy body weight. Excess body fat can contribute to additional amounts of estrogen circulating in the body. Avoiding weight gain is easier said than done, right? One place to start is by eating more real food, and less processed food. This will inevitably provide the body with more healthy fiber that is needed for gut health. High fiber diets keep the bowels moving, removing excess estrogen from the body and lessening constipation. Green, leafy vegetables and seeds are thought to detoxify excess estrogen and reduce cancer risk. Avoiding excess alcohol intake to one or less glasses a day also helps lessen hormone disruption and cancer risk.
Xenoestrogens are “foreign” estrogens produced outside the body in our environment. They are endocrine disruptors altering hormone balance. They closely mimic the body’s estrogen, which allows them to bind to estrogen receptors in the body and disturb hormone balance. Sources of xenoestrogens include plastics, pesticides, and chemicals. For example, fruits and vegetables sprayed with pesticides, make-up, nail polish, Tupperware, and plastic water bottles are all xenoestrogens. Reducing xenoestrogen exposure helps reduce the risk of hormone imbalance and cancer risk.
What about postmenopausal hormone therapy – does estrogen therapy (ET) increase the risk of breast cancer?
Estrogen therapy can be taken in the form of pills, creams, mists, patches, and vaginal rings. ET can be very beneficial in reducing hot flashes, genital symptoms, preventing bone loss, and reducing the risk of heart disease and diabetes. If a woman has her uterus and is prescribed oral estrogen, she will also be prescribed progesterone to maintain hormone balance and protect her uterus. Some research has shown hormone therapy can reduce total mortality by 30% if initiated prior to age 60.
Prescription estrogen therapy offers little risk of breast cancer. Specifically, only 4-8 cases of breast cancer occur in every 10,000 women taking systemic estrogen with synthetic progesterone. Hormone therapy is best when started by age 60 or within 10 years of menopause. Micronized low-dose estrogen prescribed to treat vaginal symptoms may be a viable option for women of all ages, including women with a history of breast cancer.
Estrogen offers the body many benefits, but if out of balance it can cause trouble. Avoid guessing what is right for you and start a discussion with your healthcare provider to better understand your personal options.