Can wearing a bra cause breast cancer?

Caroline Novas

There are several persistent email and internet rumors about potential causes of breast cancer. One is that wearing a bra, or wearing an underwire bra, causes the disease.

The idea that bras may cause cancer was fueled by the 1995 book called Dressed to Kill by Sydney Ross Singer and Soma Grismaijer. It claims that women who wear underwire bras for 12 hours a day have a much higher risk of developing breast cancer than women who do not wear bras.They maintain that bras restrict the lymph system, which results in a build-up of toxins in the breasts.¹ However, according to the American Cancer Society, there is no evidence that compression of the lymph nodes by bras causes breast cancer; in reality, body fluids travel up and into the underarm lymph nodes, not towards the underwire.² Similarly, there is no sufficient evidence that any types of bras cause breast cancer.

In Dr. Susan Love’s Breast Book, Love claims that the hypothesis about bras causing cancer stems from our desire to have control over areas of life where we have a lot of uncertainty or fear. People want something to blame, and also hope that by avoiding bras they can avoid breast cancer.³ While there are geographic variations in breast cancer rates, there are many, many factors, including diet, exercise, lifestyle, childbearing practices, as well as other behaviors and exposures that are more plausible explanations for these regional differences in breast cancer than bras. In places where people have less access to medical care, breast cancer will not be diagnosed as often, even though it might be present. And because the risk of breast cancer increases as women get older, breast cancer rates will be lower in parts of the world where people die of other causes at younger ages, whether they have worn bras or not.

Even if women who wear underwire bras are more likely to be diagnosed with breast cancer, a likely explanation would be that many women with larger breasts also tend to be heavier. Being overweight or having a lot of body fat puts a woman at increased risk for breast cancer.⁴ It would make sense that women with larger breasts are both more likely to wear underwire bras and more likely to develop breast cancer. But this doesn’t mean that underwire bras cause breast cancer!

In a study published in 2014, researchers interviewed postmenopausal female participants about their lifetime bra wearing patterns. Evaluating more than 1,000 women with breast cancer and almost 500 who did not have breast cancer, the researchers found no evidence of a connection between the number of hours spent wearing a bra or wearing an underwire bra and increased breast cancer risk.⁵

The bottom line: well-designed studies have not convinced experts that wearing bras or underwire bras increase your chances of developing breast cancer. Here are some factors that are associated with increased risk of breast cancer:⁶

Risk factors you can’t control

• Sex: Women represent 99% of all breast cancer patients and have a 12.1% chance of being diagnosed with breast cancer during their lifetime.
• Age: The chances of getting breast cancer increase with age. About 65% of women are over 55 years old when they are diagnosed.
• Race: After age 45, white women are more likely to get breast cancer than black women, but black women have a higher incidence before age 45 and are more likely to die from breast cancer.
• Family history: Certain inherited gene mutations (BRCA1 and BRCA2) increase the risk of developing breast cancer. However, these genes account for only 5-10% of overall cases. Even without those genes, having a grandmother, mother, sister, or daughter diagnosed with breast or ovarian cancer increases the risk.
• A previous history of breast cancer, abnormal breast cells (atypical hyperplasia) or certain non-invasive “pre-cancers” like lobular carcinoma in situ (LCIS) or ductal carcinoma in situ (DCIS) increase the risk of developing invasive cancer.
• Beginning menstruation early (before age 12) increases the risk of breast cancer by affecting the level of reproductive hormones a woman is exposed to during her lifetime.
• Starting menopause late (after age 55) increases the risk of breast cancer.
• Dense breast tissue (including fibrocystic breasts) increases the risk of breast cancer

Risk factors you can (possibly) control

• Women who delay having their first child until later in life or who never have children are at a higher risk for breast cancer.In contrast, having children at a younger age and breastfeeding decrease the risk of developing breast cancer
• Women who take hormonal therapy for menopause are at an increased risk for breast cancer.
• Being overweight or obese increases the risk of postmenopausal breast cancer
• Physical inactivity increases risk.
• Women who drink an average of 2 alcoholic beverages per day increase their breast cancer risk by 21%. The more a woman drinks, the greater her risk.
• High levels of radiation in the chest area before the age of 30 increase the risk.
• Women who took DES during pregnancy (this drug was mainly used in the 40s, 50s, 60s, and 70s) are at an increased risk of breast cancer. The risk to their daughters is still being studied.
• There is growing evidence that smoking and exposure to tobacco smoke probably increase breast cancer risk.
• The use of oral contraceptives may slightly increase the risk of developing breast cancer. Some studies have found no increased risk from taking birth control pills and others have shown an increased risk.

If you are worried about your risk of breast cancer, you should discuss your concerns with a health care professional and find out about ways to cut your risk. Knowing the real risk factors and making healthy lifestyle choices can help you reduce your risks. Going braless won’t.

All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.