A recent study found no association between bra-wearing and breast cancer risk among postmenopausal women.

Researchers conducted a population-based case-control study, and determined wearing a bra most likely does not increase one's risk of developing breast cancer, the American Association for Cancer Research reported.

"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," said Lu Chen, MPH, a researcher 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. "Given how common bra wearing is, we thought this was an important question to address."

In some instances the media suggested wearing a bra could increase breast cancer risk. Some have hypothesized the draining of waste products from the breast could be restricted by a bra, but there is little clinical evidence to support that idea.

"Our study found no evidence that wearing a bra increases a woman's risk for breast cancer. The risk was similar no matter how many hours per day women wore a bra, whether they wore a bra with an underwire, or at what age they first began wearing a bra," Chen said.

The study looked at various bra-wearing habits in relation to breast cancer. The team made their findings through a rigorous epidemiological study.

"The findings provide reassurance to women that wearing a bra does not appear to increase the risk for the most common histological types of postmenopausal breast cancer," the authors said.

The study participants included 454 women with invasive ductal carcinoma (IDC), 590 women with invasive lobular carcinoma (ILC) and 496 who did not have breast cancer; all of the women were between the ages of 55 and 74. The researchers conducted in-person interviews and obtained information on the participants' family and reproductive history.

The questionnaire asked the "age at which the study participant started wearing a bra, whether she wore a bra with an underwire, 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."

No aspect of wearing a bra was found to contribute to the risk of IDC or ILC.

The findings were published in Cancer Epidemiology, Biomarkers & Prevention.