Breast Cancer Risk Factors
Everyone wants to know what they can do to lower their risk of breast cancer. Some of the factors associated with breast cancer — being a woman, your age, and your genetics, for example — can't be changed. Other factors — being overweight, lack of exercise, smoking cigarettes, and eating unhealthy food — can be changed by making choices. By choosing the healthiest lifestyle options possible, you can empower yourself and make sure your breast cancer risk is as low as possible.
The known risk factors for breast cancer are listed below. Click on each link to learn more about the risk factor and ways you can minimize it in your own life. If a factor can't be changed (such as your genetics), you can learn about protective steps you can take that can help keep your risk as low as possible.
Known risks
Just being a woman is the biggest risk factor for developing breast cancer. There are about 266,120 new cases of invasive breast cancer and 63,960 cases of non-invasive breast cancer this year in American women.
As with many other diseases, your risk of breast cancer goes up as you get older. About two out of three invasive breast cancers are found in women 55 or older.
Women with close relatives who've been diagnosed with breast cancer have a higher risk of developing the disease. If you've had one first-degree female relative (sister, mother, daughter) diagnosed with breast cancer, your risk is doubled.
About 5% to 10% of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child.
If you've been diagnosed with breast cancer, you're 3 to 4 times more likely to develop a new cancer in the other breast or a different part of the same breast. This risk is different from the risk of the original cancer coming back (called risk of recurrence).
If you had radiation to the chest to treat another cancer (not breast cancer), such as Hodgkin's disease or non-Hodgkin's lymphoma, you have a higher-than-average risk of breast cancer. If you had radiation to the face at an adolescent to treat acne (something that’s no longer done), you are at higher risk of developing breast cancer later in life.
If you've been diagnosed with certain benign (not cancer) breast conditions, you may have a higher risk of breast cancer. There are several types of benign breast conditions that affect breast cancer risk
White women are slightly more likely to develop breast cancer than Black, Hispanic, and Asian women. But Black women are more likely to develop more aggressive, more advanced-stage breast cancer that is diagnosed at a young age.
Overweight and obese women have a higher risk of being diagnosed with breast cancer compared to women who maintain a healthy weight, especially after menopause. Being overweight also can increase the risk of the breast cancer coming back (recurrence) in women who have had the disease.
Women who haven’t had a full-term pregnancy or have their first child after age 30 have a higher risk of breast cancer compared to women who gave birth before age 30.
Breastfeeding can lower breast cancer risk, especially if a woman breastfeeds for longer than 1 year.
Women who started menstruating (having periods) younger than age 12 have a higher risk of breast cancer later in life. The same is true for women who go through menopause when they're older than 55.
Current or recent past users of HRT have a higher risk of being diagnosed with breast cancer. Since 2002 when research linked HRT and risk, the number of women taking HRT has dropped dramatically.
Research consistently shows that drinking alcoholic beverages — beer, wine, and liquor — increases a woman's risk of hormone-receptor-positive breast cancer.
Research has shown that dense breasts can be twice as likely to develop cancer as nondense breasts and can make it harder for mammograms to detect breast cancer.
Research shows a link between exercising regularly at a moderate or intense level for 4 to 7 hours per week and a lower risk of breast cancer.
Smoking causes a number of diseases and is linked to a higher risk of breast cancer in younger, premenopausal women. Research also has shown that there may be link between very heavy second-hand smoke exposure and breast cancer risk in postmenopausal women.
Emerging risks
Research suggests that women with low levels of vitamin D have a higher risk of breast cancer. Vitamin D may play a role in controlling normal breast cell growth and may be able to stop breast cancer cells from growing.
The results of several studies suggest that women who work at night — factory workers, doctors, nurses, and police officers, for example — have a higher risk of breast cancer compared to women who work during the day. Other research suggests that women who live in areas with high levels of external light at night (street lights, for example) have a higher risk of breast cancer.
Some pregnant women were given DES from the 1940s through the 1960s to prevent miscarriage. Women who took DES themselves have a slightly higher risk of breast cancer. Women who were exposed to DES while their mothers were pregnant with them also may have slightly higher risk of breast cancer later in life.
Diet is thought to be at least partly responsible for about 30% to 40% of all cancers. No food or diet can prevent you from getting breast cancer. But some foods can make your body the healthiest it can be, boost your immune system, and help keep your risk for breast cancer as low as possible.
Research strongly suggests that at certain exposure levels, some of the chemicals in cosmetics may contribute to the development of cancer in people.
There's a real concern that pesticides, antibiotics, and hormones used on crops and livestock may cause health problems in people, including an increase in breast cancer risk. There are also concerns about mercury in seafood and industrial chemicals in food and food packaging.
Research strongly suggests that at certain exposure levels, some of the chemicals in lawn and garden products may cause cancer in people. But because the products are diverse combinations of chemicals, it's difficult to show a definite cause and effect for any specific chemical.
Research strongly suggests that at certain exposure levels, some of the chemicals in plastic products, such as bisphenol A (BPA), may cause cancer in people.
While chemicals can protect us from the sun's harmful ultraviolet rays, research strongly suggests that at certain exposure levels, some of the chemicals in some sunscreen products may cause cancer in people.
Research has shown that the water you drink — whether it’s from your home faucet or bottled water from a store — may not always be as safe as it could be. Everyone has a role in protecting the water supply. There are steps you can take to ensure your water is as safe as it can be.
Research has shown that women who ate a lot of grilled, barbecued, and smoked meats and very few fruits and vegetables had a higher risk of breast cancer compared to women who didn't eat a lot of grilled meats.
Common Fears With No Evidence: Antiperspirants and Bras
In media stories and on Internet postings, some factors have been widely rumored to increase breast cancer risk. For example, right now, there is no evidence to back the claims that antiperspirants, underwire bras, and wearing a bra at night are causes of breast cancer.
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— Last updated on February 10, 2022, 11:08 PM
