Bras and Breast Cancer: A Theory that Lacks Support

You may be seeing reports around the web or in your email charging that the American Cancer Society and other groups are involved in a “cover-up” of a connection between wearing a bra and breast cancer. The claim that bras cause breast cancer is not new, and there’s no credible evidence to suggest a link. Nonetheless, a 2002 survey by American Cancer Society researchers showed six percent of respondents agreed that ‘‘Under-wire bras can cause breast cancer.” Another 31 percent were not sure.

So why do people believe it? The theory got a boost from a 1995 book by a husband and wife team of medical anthropologists. The pair noted that among indigenous groups who had not adopted Western lifestyles, breast cancer was rare, while cultures where the Western way of life had been embraced had breast cancer rates comparable to those in the developed world. The culprit, they concluded, was the bra.

The authors tested their hypothesis by surveying women in the U.S., but they did so without the careful controls done to make sure this kind of study is accurate. They then analyzed the results without adjusting for the factors we know can increase the risk of breast cancer risk (more on those later). They concluded that frequent ⁄ prolonged bra use impedes the elimination of toxins via the lymphatic system, and causes breast cancer. They published their findings not in a peer-reviewed journal, but in a book. Meanwhile, no other, credible studies have shown that bras increase the risk.

The emails and posts also point to a 1991 Harvard study, claiming that it showed there was a higher rate of breast cancer in women who wore bras. That’s true, but the authors of that study suggest this finding was  due to larger breast size of bra-wearers. In fact, their study did find among women who wore bras, larger cup size was associated with increased risk of breast cancer. Most experts think the culprit here isn’t bras, but having more breast tissue, which is correlated not only with increased risk of breast cancer but also with overweight or obesity, which itself causes metabolic changes that increase breast cancer risk.

Because of the attention this book generated,  ACS scientists Ted Gansler, M.D. and Ahemdin Jemal, Ph.D. conducted a small study in 2009 published in the Breast Cancer Journal (subscription required) to explore the biological mechanism behind the carcinogenic bra hypothesis. They looked at survivors of shoulder or upper extremity melanoma. Many patients with this cancer have their underarm lymph nodes removed surgically, which substantially impedes lymphatic drainage from the breast. If lymphatic obstruction caused breast cancer, one would expect those who got the surgery to have higher rates of breast cancer. Their analysis found no increase in breast cancer among those who had surgery to remove the lymph nodes. The authors caution that their study was preliminary, but concluded the “results do not support the hypothesis of lymphatic disruption being a breast cancer risk factor.”

So what’s wrong with telling people bras are a risk? We think it’s very important that women learn about the things we know can reduce their risk of this disease and focus on making changes that can really make a difference. That’s why our website includes evidence-based information on breast cancer risk factors (and risk factors for all other types of cancer), and why we recently published a review of breast cancer risk factors in our journal CA: A Cancer Journal for Clinicians. It pointed out that “acting on information that we already have could prevent thousands of [breast cancer] cases each year.”

The report was authored by Graham Colditz, M.D., a world-recognized expert in cancer prevention. It says among the most important ways to prevent breast cancer: avoiding weight gain as an adult, being physically active, limiting alcohol, and eating a healthy diet, high in fruits, vegetables, and whole grains.

Those may not be as intriguing  as a conspiracy to promote lingerie, but women deserve honest evidence, not scare stories.

For another, pretty humorous take on all this, see “Bad Chart Thursday: Bra Cancer” by Melanie Mallon at Skepchick.