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Experts at Dana-Farber explain the myths and misconceptions

Wendy Chen, MD, MPH

From the food we eat to the products we use, there are a lot of misconceptions about what may increase the risk of developing breast cancer. There are known factors, like genetics, that are well documented. But what about lifestyle issues like having a nightly cocktail or using deodorant?

So, what is fact and what is fiction? Wendy Chen, MD, MPH, a breast cancer expert at Dana-Farber Cancer Institute in Boston says an overabundance of information can be confusing, and it often is incorrect to some degree. She tackles some of the more common questions about breast cancer risks, explains the studies behind the answers, and provides risk-lowering tips.

1. Soy may increase the risk of breast cancer returning.

False. Chen, who was part of a study that looked at over 9,500 American and Chinese breast cancer survivors who ate soy every day, says that eating soy may be linked to a lower risk of recurrence of breast cancer. “Many of my patients ask about eating soy and soy foods after being treated for breast cancer,” says Chen. “But the research shows that soy is not harmful.” The study showed that women who ate at least 10 mg of soy isoflavones per day had a 25 percent reduction in their recurrence risk, as well as a minor reduction in all-cause and breast cancer-specific mortality. “This study should be comforting to women who enjoy soy in their diet and don’t want to eliminate it after a breast cancer diagnosis. However, it’s important to note that it is still too early to say that eating extra soy adds any benefits,” says Chen.

2. Alcohol consumption can increase the risk of breast cancer.

True. Dana-Farber researchers found that women who consume one alcoholic drink a day may increase their risk for breast cancer. “Women need to consider the possible effects of alcohol on breast cancer risk when weighing the risks and benefits of alcohol consumption,” says Chen, who was the lead author of the study. “Our findings indicate that in some women, even modest levels of alcohol consumption may elevate their risk of breast cancer.” Chen and her colleagues analyzed data from over 105,000 women in the Nurses’ Health Study. Those who consumed three to six glasses of wine a week were 15 percent more likely to receive a diagnosis of breast cancer. Those who drank fewer than three drinks a week had no increased risk. “It’s important to emphasize that an occasional cocktail or glass of wine is fine,” says Chen. “It’s not just what people do in the short term but how much they regularly drink over a long period of time.”

3. Fertility treatments increase a woman’s risk of breast cancer.

False. According to a recent study from the National Institutes of Health, ovulation-inducing fertility treatments like Clomid and follicle stimulating hormone (FSH) do not significantly increase a woman’s risk of developing breast cancer. The research did, however, reveal differences in cancer risk after infertility treatment based on whether or not the patient became pregnant after treatment. “We get asked this question all the time,” says Chen. “As of now, I would say this particular study is reassuring for women. It found that women who took fertility drugs, but did not get pregnant, had a slightly lower risk of developing breast cancer compared to women who stayed pregnant for at least 10 weeks.” In those cases the women only had a slightly elevated risk that was still not higher than the general population. However, Chen emphasizes that larger studies are still needed.

4. Wearing deodorant can increase the risk of breast cancer.

False. According to the National Cancer Institute, there is no conclusive research linking underarm deodorants to breast cancer. Some research suggests that aluminum-based compounds, which are often used in antiperspirants, may be absorbed by the skin and cause estrogen-like (hormonal) effects which may contribute to the development of breast cancer. Other studies have shown no connection, The National Cancer Institute believes additional research may be needed. “I agree with the National Cancer Institute that more research is needed on this topic,” says Chen. “This question comes up quite often and while there is no clear connection, this is very much an individual choice.”

5. The bigger the baby the bigger the risk of getting breast cancer.

Possibly true. “This is a tough one because the research is still evolving,” says Chen. But the latest research shows that women who have larger babies have more than twice the risk of developing breast cancer than mothers who give birth to smaller infants. Researchers say that having a heavier baby may create a hormonal environment in pregnancy that could lead to the future development of breast cancer. They found that during pregnancy in women who have heavier babies, the ratio of estrogen to anti-estrogen is unusually high. The greater the level of estrogen, the higher the risk of breast cancer. However, Chen emphasizes, “women who have larger babies should not panic. There is definitely a need for further research.” She says it’s important that women focus on maintaining a healthy diet and weight level, before, during, and after pregnancy.

The best way to reduce breast cancer risk

“It’s important that women talk with their caregivers, their primary care doctor, their oncologist and their nurse practitioner,” says Chen. “They will be able to offer the best advice based on a woman’s individual needs. But in general, the best way for a woman to lower her risk of breast cancer is to get enough exercise, eat a well-balanced diet, maintain a healthy weight, drink alcohol in moderation, get a yearly mammogram if she is 40 or older, know her body and see her doctor if there are any noticeable changes.”

At Dana-Farber, patients receive breast cancer treatment at the Susan F. Smith Center for Women’s Cancers Breast Oncology Program at Dana-Farber/Brigham and Women’s Cancer Center.

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