They may be uncomfortable, pinch your skin and leave red marks. But no, bras do not cause breast cancer.
A study of 1,500 postmenopausal women, recently published in a journal of the American Association for Cancer Research, dispels the myth that wearing a bra increases the risk for breast cancer.
The population-based study in Cancer Epidemiology, Biomarkers & Prevention compared the bra-wearing habits of 454 women with invasive ductal carcinoma and 590 women with invasive lobular carcinoma — the most common types of breast cancer — with 469 women who did not have breast cancer.
Researchers found no aspect of the brassiere — including cup size, hours worn per day, age at which one started wearing a bra, or whether it had an underwire — was associated with increased risks for breast cancer.
The idea for the study stemmed from suggestions in the lay media, and rumours on the internet, that bras cause breast cancer because they inhibit lymph circulation to lymph nodes under the arm, interfering with the removal of waste and toxins causing them to accumulate.
It’s a notion promoted in the 1995 book Dressed To Kill: The Link between Breast Cancer and Bras, which has been criticized by the American Cancer Society for not taking into account other variables, like known risk factors.
Some also believe breast cancer is more common in the developed world, compared with developing countries, because of the bra-wearing habits of women in richer countries.
“Given how common bra wearing is, we thought this was an important question to address,” said the study’s lead author Lu Chen, a researcher in the Public Health Sciences Division at Fred Hutchinson Cancer Research Center in Seattle.
This study was part of a larger project called the SHARE Study (Seattle Area Hormone and Reproductive Epidemiology Breast Cancer Study) looking at risk factors specific to three types of breast cancer. The project has also resulted in various other published studies.
The proposed link between bras and breast cancer seemed “implausible,” and has “limited biological evidence to support it,” said Chen. Plus, experts have said the varying breast cancer rates around the world can be explained, in part, by differences in major risk factors, such as age of first menstrual period, age of first birth and obesity.
Still, it was important to explore a possible connection between brassieres and breast cancer because “very few scientific studies have addressed these concerns,” said Chen, who is also a doctoral student of epidemiology at the University of Washington School of Public Health.
The only other credible study to look at this was published in 1991. It suggested premenopausal women who didn’t wear bras had less risk of breast cancer compared with bra users, but the difference wasn’t statistically significant. The authors of that study noted that perhaps the non-bra wearers had lower risk because they were thinner and had smaller breasts. They also explained that although postmenopausal bra wearers with larger cup sizes showed an increased risk of breast cancer, this was likely because the women were obese.
That means that to date, no valid scientific study has provided evidence that bra wearing causes breast cancer.