No Support for Bras Causing Postmenopausal Breast Cancer
September 04, 2014
When a postmenopausal woman complains, "my bra is killing me," it can be safely chalked up to a poor fit, not to an increased risk for breast cancer.
In a large population-based case-control study of postmenopausal women conducted in the Pacific Northwest, investigators could find no link between bras and the risk for either invasive ductal carcinoma (IDC) or invasive lobular carcinoma (ILC).
"No aspect of bra wearing, including bra cup size, recency, average number of hours/day worn, wearing a bra with an underwire, or age first began regularly wearing a bra, was associated with risks of either IDC or ILC breast cancer," write Lu Chen, MPH, and colleagues from the division of public health sciences at the Fred Hutchinson Cancer Research Center in Seattle.
Their findings were published online September 5 in Cancer Epidemiology, Biomarkers & Prevention.
Admittedly, the potential for frat-boy jokes is huge, but patient concerns about potentially modifiable risk factors - however unlikely - deserve to be taken seriously, Chen said in an interview with reporters.
"Some people worry that the reason breast cancer is more common in developed than in developing countries is the difference in bra-wearing patterns; we saw that in the lay media as well," Chen explained. "Even though the biologic plausibility of this notion is quite weak, bra wearing is essentially ubiquitous today, so we thought this was an important question to address," she said.
As Seen on the Internet
Proponents of the carcinogenic bra theory contend that a constricting bra - particularly one with underwire - can block the flow of lymphatic fluid and inhibit the disposal of toxins, leading to increased exposure and, potentially, an increased risk for breast cancer.
In a previous study, investigators examined data on 2325 breast cancer cases and 7008 control subjects, and found that "among bra users, larger cup size was associated with an increased risk of breast cancer (P about .026), although the association was found only among postmenopausal women and was accounted for, in part, by obesity" (Eur J Cancer. 1991;27:131-135).
In addition, a 2005 book, provocatively entitled Dressed To Kill: The Link between Breast Cancer and Bras, struck fear in the hearts of bra-wearing women and lingerie manufacturers. The promotional copy says that the book "presents evidence supporting the authors' theory that bras suppress the lymphatic system, causing toxins to accumulate in the tissues of the breasts, leading to a variety of health problems."
All But 1 Woman Wore a Bra
To see whether that idea holds water, Chen and colleagues drew on data from a population-based study of breast cancer risk factors in postmenopausal women in the Seattle-Puget Sound area of Washington.
They identified 454 women with IDC, 590 with ILC, and 469 control subjects selected from the community by random-digit dialing.
A face-to-face interview was conducted with both case and control subjects to find out about potential breast cancer risk factors, including reproductive history, medical history, family history of cancer, body size, and use of hormonal replacement.
The women were also asked about their bra cup and band sizes, the age at which they started regularly wearing a bra, whether they wore underwire bras, and the number of hours per day and days per week they wore a bra at different times of their lives.
The team found no evidence of a link between breast cancer risk and bra size, type, or frequency of wearing.
On multivariate analysis, there was a nearly 2-fold risk for both IDC (odds ratio [OR], 1.9; 95% confidence interval [CI], 1.0 - 3.6) and ILC (OR, 1.8; 95% CI, 1.0 - 3.6) in women who reported wearing A-cup sized bras, but neither association was significant.
The study was limited by participant self-reporting of bra-wearing habits, which could be subject to recall bias, and by the fact only 1 of the more than 1500 women interviewed reported never wearing a bra, compelling the investigators to base the primary comparison on hours of bra wearing rather than comparing wearing with not wearing a bra, Chen told Medscape Medical News.
Passing the Buck
Although the theory linking bras with risk for breast cancer was debunked by Chen's group, a cancer specialist not involved in the study said he understands why the team took it on, and why the theory persists.
"If you do a Web search, there are popular myths out there about the causes of breast cancer - this is just one of many - although there is no, or rather very minimal, rigorous evidence to refute the idea or the fear that bras cause breast cancer," said Graham Colditz, MD, DrPH, associate director of prevention and control at the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis.
"Globally, breast cancer is the most common cancer diagnosed in women," he explained. Unlike some other cancers, "we don't have a major strategy out there to prevent it, even though we know what causes it."
People are often more willing to look for something else to blame rather than acknowledge that a combination of biology and modifiable risk factors, such as alcohol use and obesity, are known to contribute to breast cancer risk.
"From a standpoint of risk perception and action, it's easier to think the causes are external to what we're doing, rather than accept, both individually and as a society, that it's our lifestyle that's the root cause here for the high burden of breast cancer and other cancers," Dr. Colditz said.
The study was funded by a grant from the National Cancer Institute. Ms. Chen, her coauthors, and Dr. Colditz have disclosed no relevant financial relationships.
Cancer Epidemiol Biomarkers Prev. Published online September 5, 2014. Abstract