Monday, March 14, 2016

Do underwire bras cause breast cancer?

Last week I was out with my mama friends and of course our boobs came up in conversation (apparently one drink in and we start talking about lady parts). One friend mentioned that she only wears bras without underwire because she had a breast cancer scare a couple years back and was advised to not wear underwire bras.  Which of course led me to wonder whether there was any science behind this.

I've been wearing underwire bras forever, and was told that if I wanted to keep the girls up, proper undewire support was the only way to go. Was I causing myself to be at higher risk for breast cancer?

After doing some research I found that this was quite the contentious topic and that neither my friend nor I were quite right.

While there are quite a number of websites that claim that tight fitting underwire bras clog our lymphatic drainage (our lymphatic system runs through our body carrying infection fighting cells and removing "debris"), increasing risk for breast cancer. This claim was based on a study that showed that women who wore underwire bras were at a much higher risk for getting breast cancer, and that in cultures where women didn't wear bras, they had very little breast cancer risk. Sounds compelling right? Ah, if only we could just let our boobs hang out and not get breast cancer. Too bad what the study didn't take into account were things such as genetics, fat, diet, age, or any of the other things that have been shown to increase breast cancer risk. All in all this study was good at showing correlation  (bras and breast cancer are associated with one another), but  NOT causation (bras actually breast cancer). A much more robust study published in 2014 found that there was NO association with bra wearing and cancer in women that over 55 years old.

And then there is the whole issue of whether wearing these contraptions even helps keep the girls up. Not so much, since there is this thing called gravity and age. And let me tell you, there isn't much to do about that. Weight fluctuation, breast feeding, and aging all take their toll on breast tissue, and wearing a bra doesn't actually change that.

Bottom line,  do what is comfortable for you and what makes you feel good. If wearing an underwire bra gives you the support you need, great. If you are more comfortable with a soft cup or no cup, that's wonderful too!


  1. Hi Maya. You mentioned my research and book, Dressed to Kill, in your article.

    I want to let you know that the other study you mentioned that allegedly is more "robust" done in 2014 was flawed by not having any bra-free women, so there was no control group. That's like studying the effect of smoking tobacco on lung cancer by only looking at lifetime smokers and excluding nonsmokers.

    On the other hand, there are now numerous studies that support the bra-cancer link, including a 2015 peer reviewed epidemiological study. Here is a list of some of these studies.
    1. 1991 Harvard study (CC Hsieh, D Trichopoulos (1991). Breast size, handedness and breast cancer risk. European Journal of Cancer and Clinical Oncology 27(2):131-135.). This study found that, "Premenopausal women who do not wear bras had half the risk of breast cancer compared with bra users..."

    2. 1991-93 U.S. Bra and Breast Cancer Study by Singer and Grismaijer, published in Dressed to Kill: The Link Between Breast Cancer and Bras (Avery/Penguin Putnam, 1995; ISCD Press, 2005). Found that bra-free women have about the same incidence of breast cancer as men. 24/7 bra wearing increases incidence over 100 times that of a bra-free woman.

    3. Singer and Grismaijer did a follow-up study in Fiji, published in Get It Off! (ISCD Press, 2000). Found 24 case histories of breast cancer in a culture where half the women are bra-free. The women getting breast cancer were all wearing bras. Given women with the same genetics and diet and living in the same village, the ones getting breast disease were the ones wearing bras for work.

    4. A 2009 Chinese study (Zhang AQ, Xia JH, Wang Q, Li WP, Xu J, Chen ZY, Yang JM (2009). [Risk factors of breast cancer in women in Guangdong and the countermeasures]. In Chinese. Nan Fang Yi Ke Da Xue Xue Bao. 2009 Jul;29(7):1451-3.) found that NOT sleeping in a bra was protective against breast cancer, lowering the risk 60%.

    5. 2011 a study was published, in Spanish, confirming that bras are causing breast disease and cancer. - It found that underwired and push-up bras are the most harmful, but any bra that leaves red marks or indentations may cause disease.

    6. A 2014 study in Scotland suggests that cleavage-enhancing bras are a potential cause of increased upper outer quadrant breast cancer, due to the constricting effect of inbuilt wiring on breast tissue and the lymphatic system.

    7. A 2015 peer reviewed epidemiological study from Kenyan has confirmed a significant bra-cancer link.

    8. The Bra Sign in Breast Cancer “We have noticed in several cases that the bra leaves more pronounced marks on the skin of the affected breasts in women with breast cancer...If this sign is noticed, thorough investigation to exclude breast cancer should be pursued.”

    9. Tight Bra in a 34-Year-Old Woman: An Unusual Cause of Mondor's Disease. Blood clots in the superficial veins of the breast and chest (Mondor's disease) caused by wearing a tight bra.

    10. Axillary lymph drainage as a prognostic factor of survival in breast cancer. “All patients with distant metastases had obstructed lymph vessels at the time of original diagnosis. These findings suggest that the chance for survival is determined both by the status of axillary lymph drainage as well as the number of metastatic axillary lymph nodes.” This shows that lymphatic drainage is important for preventing the spread of cancer.

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  3. Syd, thank you for your comment and insight. I do agree that the Chen article is not the best study in establishing causality, or lack there of in the BC/bra link. As an epidemiologist and methodologist I am always looking for the most scientifically and statistically sound studies to report to my audience. Many people do not have the scientific literacy to be able to understand the nuances of a case study vs. a case-control study, so I try to make that part easier to understand. Additionally, as a peer reviewer for several top journals, I am also particular as to where the studies I cite have been published, as I am partial to rigorous peer review. Of the studies you cited, only the Kenyan study makes me pause. The Kenyan study, while having statistical significance, in absolute numbers the difference was rather small, and it did not take into account breast size.
    Separately, most women do not wear bras 24/7. Those that do usually do so because of larger breast size, and that has its own confounding factors associated with both weight, diet, and ethnicity.
    I am happy to revisit, or perhaps write a post about the importance of wearing proper fitted bras (no one should wear something that hurts or leaves marks!).

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