8 Disproven Breast Cancer Risk Factors You Need to Know

BCRF separates fact from fiction on eight controversial, disproven breast cancer risk factors—and shares what science actually says about risk and certain lifestyle choices

Breast cancer research has made incredible strides in recent decades, helping us understand what truly increases risk—and what doesn’t. But despite all this progress, misinformation about breast cancer risk factors still leaves many confused about the basics. Do bras cause breast cancer? What about using antiperspirant deodorant or carrying your phone near your chest?

While it’s normal to consider whether everyday habits could raise your risk, the good news is that many commonly cited dangers have been debunked. Here, BCRF separates fact from fiction by breaking down eight debunked breast cancer risk factors—and what you actually need to know about risk and certain lifestyle choices.

Does antiperspirant deodorant cause breast cancer?

No credible scientific evidence has linked the use of deodorant and breast cancer risk. While social media posts and internet rumors warn of “carcinogenic” ingredients lurking in antiperspirants, high-quality research doesn’t back up those claims.

The concern largely stems from some ingredients used in antiperspirant deodorants, particularly the aluminum-based compounds that temporarily plug sweat ducts. Some have claimed that this ingredient can create a similar effect to estrogen, a hormone that can bind to some breast cancer cells and help them spread. But according to the NCI, there’s no conclusive evidence for this theory. The American Cancer Society (ACS) also points out that the amount of aluminum absorbed through the skin is minimal—far less than what’s consumed through food.

A 2002 study published by the Journal of the National Cancer Institute, which evaluated data on 813 breast cancer patients, found there was no connection between the use of deodorant and breast cancer risk.

So, if wearing antiperspirant deodorant is part of your daily routine, there’s no reason to worry that it will cause breast cancer. With that being said, the aluminum from antiperspirant could look like microcalcifications (a potential sign of breast cancer) on a mammogram. Your mammogram provider may recommend you skip it on the day of your appointment to avoid any possible confusion.

Do bras cause breast cancer?

No, wearing a bra—whether it’s underwire, push-up, or sports—does not increase your risk of breast cancer. This myth gained some traction after the 1995 book “Dressed to Kill” claimed that the compression from bras suppressed the lymphatic system, leading to a build-up of toxins that eventually cause breast cancer. They pointed to this as the reason why breast cancer rates were higher in developed countries, where women may be more likely to wear bras.

However, scientific research doesn’t back up this claim. In a 2014 study, researchers evaluated the bra-wearing habits of 1,044 breast cancer patients and 469 control women. They found no association between underwire bras and breast cancer (or any other type of bras, for that matter).

You can keep wearing your favorite bras (or ditch them altogether) without any impact on your risk of breast cancer.

Do breast implants cause breast cancer?

The relationship between breast implants and cancer is complex. On a positive note, research shows that implants do not increase the risk of breast cancer, according to a meta-analysis published by the American Society of Plastic Surgeons in 2001. It found no difference in breast cancer rates, recurrence, or survival between women with implants and those without.

However, certain types of breast implants may put women at risk of other types of cancer. In 2011, the Food and Drug Administration (FDA) identified a link between textured implants and anaplastic large cell lymphoma, a type of non-Hodgkin’s lymphoma. Breast implant–associated anaplastic large cell lymphoma (BIA-ALCL) isn’t breast cancer, but it can develop in the scar tissue and fluid near the implant, and potentially spread throughout the body. Estimates suggest the risk of BIA-ALCL may range from one in every 355 to 30,000 patients who’ve undergone implant-based breast reconstruction. The FDA is also investigating a possible connection between breast implants and squamous cell carcinoma, but more research is needed before drawing any firm conclusions.

The bottom line: While breast implants don’t cause breast cancer, they may put you at increased risk of other types of cancer. Talk to your doctor about your individual risk.

Does having larger breasts cause breast cancer?

Breast cancer can affect anyone, regardless of their cup size—and there’s no solid evidence that having larger breasts puts you at greater risk. While some research has found that there may be a higher incidence rate of breast cancer in women with larger breasts, it’s unlikely that the breast size directly impacts the risk. Instead, other factors may be at play.

For instance, one study found that mammograms tend to be more sensitive and specific in larger breasts, potentially making cancer easier to detect. Another study found that tumors in larger breasts tend to be bigger at diagnosis, which could contribute to higher rates of advanced breast cancer diagnoses in women with larger cup sizes. And another report suggests that while larger breast size is genetically linked to higher body mass index—which may increase the risk of breast cancer—there’s no strong evidence that breast size alone puts someone at higher risk.

Bottom line? Breast size isn’t a proven risk factor for breast cancer, even though factors associated with larger breasts—such as a higher BMI, larger tumor size at the time of diagnosis, and mammogram sensitivity—may influence an individual’s risk and how easily cancer is detected.

Does carrying your cell phone in your bra cause breast cancer?

So far, research has not found strong evidence linking cell phones to breast cancer. Mobile phones emit radio frequency (RF) waves, a type of non-ionizing radiation, which some worry may cause cancer. However, unlike ionizing radiation from X-rays or UV rays, RF waves don’t damage DNA in a way that’s known to cause cancer.

Most research to date has focused on cell phones and brain tumors, finding no clear link between the two. The largest case-control study so far, the INTERPHONE study, which analyzed cell phone use habits in more than 5,000 brain tumor patients in 13 countries, found no increased risk of brain cancer with the use of mobile phones. Two other large cohort studies—the Danish cohort study and the U.K. Million women Study—echoed those findings.

While limited research has explored cell phones and breast cancer, science has not established a direct connection. One small Taiwanese study suggests that excessive smartphone use and keeping mobile devices close to the breasts could increase the risk of breast cancer. And a report from 2013 describes a case series of four young women diagnosed with breast cancer who kept their cell phones in their bras, but this report was purely observational and does not prove cause and effect.

For now, the science doesn’t support the claim that carrying a phone in your bra increases breast cancer risk. Still, experts suggest keeping phones away from direct skin contact as a precaution—plus, it’s probably more comfortable to do that anyway.

Does sugar cause breast cancer?

Despite claims you may have read on social media, sugar does not fuel cancer. (And no, cutting it won’t shrink tumors, either.) All of our cells can use blood sugar (glucose) for energy. Increasing sugar intake doesn’t make cancer cells multiply faster, just as depriving them of sugar won’t stop them from growing.

With that being said, some research suggests a potential link between sugar intake and breast cancer risk. A 2022 review found a correlation between high sucrose intake in adolescence and dense breast tissue—a known breast cancer risk factor. It also noted that women who frequently consumed sweets had a significantly higher risk of developing breast cancer, and higher sugar intake was associated with an increased risk of death after a breast cancer diagnosis. However, the researchers emphasized that these findings don’t prove that sugar is directly to blame for breast cancer cases. The fact that diets high in added sugars tend to be associated with weight gain and obesity, insulin resistance, and inflammation likely plays a role.

Rather than focusing on cutting any one ingredient to reduce the risk of breast cancer, the best approach is a balanced diet rich in whole, nutrient-dense foods. Guidelines also recommend limiting intake of red and processed meats, sugary drinks, processed foods, refined grains, and alcohol to reduce your risk of cancer.

Can a breast injury cause breast cancer?

There are countless stories online from women who found out they had breast cancer after getting injured in some way, like a car accident or a blow to the chest while playing sports. However, there’s no research that proves a direct link between a breast injury and breast cancer. Cancer happens when a change in our DNA causes cells to multiply uncontrollably and develop into tumors. Physical trauma, while painful, doesn’t lead to DNA damage.

Rather, it’s more plausible that getting medical attention after a breast injury draws attention to a pre-existing lump, which later leads to a cancer diagnosis. Breast injuries can also result in fat necrosis, which are non-cancerous lumps that form under the skin after an injury or surgery. While fat necrosis can sometimes resemble breast cancer on a mammogram, it’s harmless and usually heals on its own. A breast injury itself does not lead to the development of breast cancer.

Do abortion and miscarriage cause breast cancer?

No, neither abortion nor miscarriage (also called spontaneous abortion) increase a woman’s risk of breast cancer, even though you may read rumors suggesting otherwise.

The myth is rooted in the role hormones play in breast cancer development. The levels of certain hormones, like estrogen and progesterone, can affect a woman’s risk of the disease. Since pregnancy causes significant hormonal changes, researchers have been studying whether there’s a potential connection between abortion and breast cancer since the late 1950s.

Decades of research have shown that it does not. In 2003, a panel of more than 100 leading experts gathered by the National Cancer Institute (NCI) reviewed the evidence and concluded that there is no link between miscarriage, abortion, and breast cancer risk.

More recent large-scale studies have also supported this conclusion, including a 2004 Lancet reanalysis of data on 83,000 women across 53 studies; a 2018 report from the U.S. National Academies of Sciences, Engineering, and Medicine; and a 2020 meta-analysis in Medicine looking at 14 previous studies. More recently, in 2025, the American College of Obstetricians and Gynecologists (ACOG) reaffirmed that scientific evidence does not support any link between induced abortion and breast cancer—a statement it has stood behind for years.