Over 90% of North American women wear a bra and despite the widespread use of bras and concerns in the lay media that bra wearing may increase breast cancer risk, there is a scarcity of credible scientific studies addressing this issue.
“There have been some concerns that one of the reasons why breast cancer may be more common in developed countries compared with developing countries is differences in bra-wearing patterns.” “Given how common bra wearing is, we thought this was an important question to address,” said Lu Chen, MPH, research assistant in the Public Health Sciences Division at Fred Hutchinson Cancer Research Center and a doctoral student in the Department of Epidemiology at the University of Washington School of Public Health and corresponding author of this new study.
Chen and colleagues examined the association between various bra-wearing habits and breast cancer risk among postmenopausal women.
The study participants included 454 women with invasive ductal carcinoma (IDC) and 590 women with invasive lobular carcinoma (ILC), the two most common subtypes of breast cancer, from the Seattle-Puget Sound metropolitan area; 469 women who did not have breast cancer served as controls. All women were postmenopausal, ages 55 to 74.
Information on bra-wearing habits and other breast cancer risk factors was collected from study participants through in-person interviews. Questions included age at which the study participant started wearing a bra, whether she wore a bra with an under wire, her bra cup size and band size, the number of hours per day and number of days per week she wore a bra, and if her bra-wearing patterns ever changed at different times in her life.
The researchers found no aspect of bra wearing, including bra cup size, regency, average number of hours/day worn, wearing a bra with an under wire, or age first began regularly wearing a bra, was associated with risks of either invasive ductal carcinoma or invasive lobular carcinoma.
The researchers write “Our results did not support an association between bra wearing and increased breast cancer risk among postmenopausal women.”
According to the American Cancer Society “There are no scientifically valid studies that show wearing bras of any type causes breast cancer.”
The society references a book called “Dressed to Kill” by Sydney Ross Singer and Soma Grismaijer that proposes a link between bras and breast cancer. According to the authors, the restrictive nature of a brassiere inhibits the lymphatic system. The society notes the book is written by a husband and wife team of medical anthropologists who link breast cancer to wearing a bra.
Singer and Grismaijer examined the bra wearing attitudes and behaviors of over 4,700 US women in 5 major cities. Their findings were:
3 out of 4 women who wore their bras 24 hours per day developed breast cancer.
1 out of 7 women who wore bras more than 12 hour per day but not to bed developed breast cancer.
1 out of 152 women who wore their bras less than 12 hours per day got breast cancer.
1 out of 168 women who wore bras rarely or never acquired breast cancer.
We do not know of any epidemiologic studies published in scientific journals that suggest bras directly contribute to breast cancer risk or that lymphatic compression by bras might cause breast cancer,” writes the society.
According to the society the size of a woman’s breasts or weather she is slim or heavy , there are no no convincing epidemiologic evidence that her choices regarding bra use will influence her breast cancer risk.
They write” Furthermore, the alleged mechanism suggested in the book and in chain e-mails (blocked lymphatic vessels causing toxins to accumulate) is inconsistent with scientific concepts of breast physiology and pathology.”