Every time you turn around, it seems something else is blamed for causing cancer. Breast cancer is among the scariest simply because it’s the most common—and it kills more than 40,000 women a year.
“There is understandably a large interest in trying to identify ‘modifiable risk factors’ or environmental exposures that could be linked to breast cancer risk,” says Arpana Naik, M.D., a breast surgeon at the Oregon Health & Science University Knight Cancer Institute. “If a specific exposure could be identified, then in theory, avoiding it or modifying one’s behavior could reduce one’s chance of breast cancer.”
In other words, it would be a major relief if we could just find something to blame and then stay really far away from that something forever. One supposed culprit that keeps popping up online is the use of deodorants and antiperspirants as a cause of breast cancer. But is there really anything to that worry? Here’s what scientists do and don’t know.
For starters, let’s just point out that the claim that using antiperspirant causes breast cancer is listed under “common cancer myths and misconceptions” on the National Cancer Institute website.
You can see that for yourself right here. And we quote: “Researchers at the National Cancer Institute (NCI), a part of the National Institutes of Health, are not aware of any conclusive evidence linking the use of underarm antiperspirants or deodorants and the subsequent development of breast cancer. The U.S. Food and Drug Administration (FDA), which regulates food, cosmetics, medicines, and medical devices, also does not have any evidence or research data that ingredients in underarm antiperspirants or deodorants cause cancer.”
But that doesn’t mean it’s always been a silly concern to dismiss. “There may have been some kind of legitimate concern at one time with deodorant,” says Rulla Tamimi, Sc.D., an associate professor of medicine and of epidemiology at Harvard Medical School. “But the weight of evidence is minimal, and really none of it in humans is very thorough.”
Meanwhile there are a lot of things that we know for surecan increase your breast cancer risk.
According to the NCI, these known risk factors are:
- Older age
- A personal history of breast cancer or benign (noncancer) breast disease
- A family history of breast cancer
- Inherited gene changes (such as mutations in the BRCA1 and BRCA2 genes, or what people (imprecisely) refer to as “the breast cancer genes“)
- Dense breasts
- Exposure of breast tissue to estrogen made in the body
- Taking hormone therapy for symptoms of menopause
- Radiation therapy to the breast or chest
- Drinking alcohol
- Being white
If your goal is to reduce your risk of developing breast cancer, the best place to start is by quitting drinking and and keeping your weight under control. Also, talk to your doctor about your own particular family history and risk factors, and determine a potential prevention or early detection plan if it makes sense. Doing those things will go farther than anything else in helping you stay healthy, or at least in helping you get the treatment you need when it can be most effective.
More on this in a bit.
So where does this idea that antiperspirant is linked to cancer even come from?
In 2001, a researcher named Philippa Darbre proposed that “underarm cosmetics” might contribute to cancer. She alsopublished a study showing that more breast cancer occurred in the upper outer quarter of the breast—the area closest to the armpit. She has since published dozens of papers based on laboratory studies (i.e. cells in petri dishes) that claim to support her hypothesis. Another researcher who agrees with her, Kris McGrath at Northwestern’s Feinberg School of Medicine, pointed out that an increase in antiperspirant use mirrors the rise in breast and prostate cancers.
Finding correlations between two things doesn’t mean that one caused the other.
Darbre was right that more cancer shows up in that upper outer quadrant first—around half start there, actually. But breast tissue isn’t spread equally among the four quadrants of the breast. The upper outer one has the most breast tissue. When you consider the greater amount of breast tissue in that area, the proportion of cancers that show up there is what you’d expect.
As for the increase in deodorants/antiperspirants and breast cancer, lots of things have increased over that time. Like TVs. Or women wearing pants. It’s possible to match up some pretty crazy correlations that obviously aren’t related. And other increases probably have played a big or small role, like birth control pills, more use of hormone replacement therapy after menopause, having fewer children, obesity rates and living longer. Plus, greater awareness and better tests have led to better detection of cancer. So a correlation isn’t enough evidence on its own.
Although lab studies have unearthed some evidence for why this correlation may exist, it hasn’t been borne out in the real world.
The hubbub about deodorants and antiperspirants surrounds two ingredients in them: aluminum and parabens.
Deodorants and antiperspirants work in different ways. The sweat glands under the arms (and in the groin area) are apocrine glands, the kind that expel fats and proteins along with sweat. Bacteria love those fats and proteins, and it’s the byproduct of their feast that produces your BO. Deodorant covers up the stink, but antiperspirants stop you from sweating in the first place. Aluminum is the active ingredient that helps antiperspirants plug up the sweat glands and reduce your perspiration. Parabens, meanwhile, are a group of preservatives used in many personal care products, such as cosmetics, shampoos and possibly some deodorants. Both aluminum and parabens are endocrine disruptors, which means they can mimic estrogen and mess with your hormone levels. Since increased hormone levels can increase the risk of breast cancer, the overall idea that these ingredients could matter isn’t crazy.
The hypothesis on deodorants/antiperspirants suggests that the pores become clogged with aluminum or parabens and increase estrogen in the body, either from these compounds or from hormones in the skin that can’t escape through sweat.Dozens of studies have looked for evidence that parabens might contribute to cancer. The findings are inconclusive, but some have found evidence of a link in lab experiments, and one study found increased levels of parabens in breast tumors.
“However, the doses of parabens required to initiate a mutation that leads to cancer would be at much higher amounts than occur in deodorant spray, making this idea less likely in reality,” explains Guy Eslick, a professor of cancer epidemiology at The University of Sydney in Australia, who published a review of the research on this topic. Besides, most major brands of deodorants or antiperspirants don’t have parabens anyway. (You can check the ingredients of your favorite brand here.)
Aluminum does appear to activate a couple types of breast cancer cells—but only in a petri dish, just as parabens do. What happens in a petri dish, though, doesn’t necessarily happen in a person, and it would require the body to absorb large amounts of aluminum. The body already has aluminum in it, and can absorb more through the skin, but not much, especially compared to other environmental sources.
“Currently, there is no known mechanism behind any link between deodorant use and breast cancer development,” Eslick says.
Very few studies have been done using real human data, and some of them aren’t all that reliable.
If you really want to show a link, you need epidemiological evidence, that is, studies done on humans showing the actual spread of disease among defined populations. Three have been done, with one finding some supportive evidence and two finding the opposite. What’s more, “the science in some of those reports is of questionable quality,” Naik says.
The study held up as evidence supporting a link involved a survey of 437 women who had survived breast cancer conducted by McGrath at Feinberg. He found that women using antiperspirants more often and earlier in life, especially if they shaved more often, were diagnosed with breast cancer several years earlier than the other women. But the study has many flaws, including the fact that it didn’t include a comparison group of women without breast cancer. Not having a control group in research is a big nope when it comes to taking research results seriously. One of the biggest criticisms is that McGrath didn’t take into account that girls who start using deodorant or shaving earlier tend to go through puberty sooner. There is “strong and consistent evidence” that earlier menarche (when a girl first starts getting her period) is associated with a higher risk of breast cancer, Tamimi says.
The other two studies—the ones that didn’t find a link—used much more reliable methods. In a study of 104 women in Iraq, half the women had breast cancer and half didn’t. But 82 percent of the women without cancer used antiperspirants, and only 52 percent of the women with cancer did. That’s a very small group of women for a study, but it was large enough to also find a link between breast cancer risk and both birth control pills and a family history of breast cancer, two known risk factors.
The biggest and best study involved 813 women with cancer and 793 women without. Once again, more of the womenwithout cancer used antiperspirant regularly. The cancer-free women were also more likely to use antiperspirant instead of deodorant or to use antiperspirant within an hour after shaving (nicks from shaving could possibly make it easier for ingredients to be absorbed). Therefore, no link between deodorant/antiperspirant and breast cancer showed up.
Three studies isn’t much, but some experts think it may not be worthwhile to conduct more.
“Research efforts would probably be best used looking at either other environmental risk factors that haven’t been investigated or trying to unravel the genetic component in a meaningful way so that each person’s individual risk could be identified,” Naik says. “Given the state of the evidence, it doesn’t seem like it would be fruitful for more research efforts to go down this pathway.”
And at the end of the day, when it comes your probable risk of developing breast cancer, there are more important things to worry about than what you use to stave off BO—and some things that we just can’t change.
Regular physical activity, moderate to low alcohol consumption and maintaining a healthy body weight reduce the risk of breast cancer, Tamimi says. Emerging evidence also suggests that consumption of carotenoids—the compounds that give fruits and vegetables their bright colors—may decrease risk for estrogen receptor negative breast cancer, a particularly aggressive type.
Meanwhile, hormone replacement therapy after menopause slightly increases risk, and oral birth control may to an even lesser extent. Beyond this, women encounter all kinds of synthetic chemical compounds each day, and most aren’t easily avoidable. So freaking out about whether or not they’re contributing to an increased risk is kind of pointless. At least until we know much, much more about them.
“A lot of these other chemicals, like parabens or BPA, are unfortunately all around us, but there is such limited evidence that it’s difficult to say what the impact of them is and it’s hard to measure. I don’t want women to be carrying a burden of unnecessary fear about day-to-day things they come into contact with since studies haven’t shown definitive scientific links with these products.” Naik says.
Plus, whatever effects they may or may not have on breast health are small compared to what each woman has been dealt biologically, she explains. “The genetic makeup of each person kind of trumps everything.”