Armpit Shaving and Breast Cancer

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Last updated: • 6 min read

Image Credit: National Cancer Institute / Unsplash. This image has been modified.

Shaving before applying underarm antiperspirants can increase aluminum absorption. Could this explain the greater number of tumors and the disproportionate incidence of breast cancer in the upper outer quadrant of the breast near the armpit?

A famous case report called “The Mortician’s Mystery,” published in the New England Journal of Medicine back in the 1980s, described a man whose testicles started shrinking and breasts started growing. It turns out the mortician failed to wear gloves as he massaged embalming cream onto corpses. It was concluded there must have been an estrogenic compound in the cream that was absorbed through his skin into his body, one of the first such cases described.

This case was cited as inspiration by a group of researchers who came up with a new theory to explain a breast cancer mystery: Why do most breast cancers occur in the upper outer corner of the breast? The standard explanation was simply because that’s where most of the breast tissue is located, as the so-called tail of the breast extends up to the armpit, but that doesn’t explain the fact that it wasn’t always this way. Indeed, there has been a shift toward the appearance of breast cancer in the upper corner of the breast. And, it also doesn’t explain why “greater genomic instability”––chromosome abnormalities––has been “observed…in outer quadrants of the breast,” which may signal precancerous changes. There definitely seems to be something happening to that outer side of the breast, and it’s something relatively new, occurring in the last 50 years or so.

“Is it possible that the increasing use of [underarm] antiperspirant which parallels breast cancer incidence could also be an explanation for the greater number of ductal tumours…and disproportionate incidence of breast cancer in the upper outer quadrant” of the breast near the site where stick, spray, or roll-on is applied? I discuss this possibility in my video Antiperspirants and Breast Cancer, where you can see a graph of U.S. breast cancer incidence and antiperspirant/deodorant sales at 1:38.

There is a free flow of lymph fluid back and forth between the breast and the armpit. If you measure aluminum levels in breasts removed during mastectomies, the “aluminum content of breast tissue in the outer regions [near the armpits]…was significantly higher,” presumably due to the “closer proximity to the underarm” area.

This is a concern because, in a petri dish at least, it has been demonstrated that aluminum is a so-called metalloestrogen, having pro-estrogenic effects on breast cancer cells. Long-term exposure of normal breast tissue cells in a test tube to aluminum concentrations in the range of those found in breasts results in precancerous-type changes. Then, as you can see at 2:41 in my video, once the cells have turned, those same concentrations “can increase the migratory and invasive activity of…human breast cancer cells” in a petri dish. This is important because women don’t die from the tumor in the breast itself, “but from the ability of the cancer cells to spread and grow at distant sites,” like the bones, lungs, liver, or brain. But, we don’t care about petri dishes. We care about people.

In 2002, a paper was published in the Journal of the National Cancer Institute in which the underarm antiperspirant habits of 800 breast cancer survivors were compared with those of women who had never gotten breast cancer, the first study of its kind. The finding? No indication of a link between the two.

Based on this study, Harvard Women’s Health Watch assured women that antiperspirants do not cause breast cancer and “women who are worried that antiperspirants might cause breast cancer can finally rest easy.” But two months later, another study was published that found that “frequency and earlier onset of antiperspirant/deodorant usage with underarm shaving was associated with an earlier age of breast cancer diagnosis.” As you can see at 3:56 in my video, it’s as much as 20 years earlier in women using antiperspirant and shaving their armpits more than three times a week. And, the earlier they started before versus after age 16 appeared to move up their breast cancer diagnosis by 10 or 20 years. The researchers concluded that “underarm shaving with antiperspirant/deodorant use may play a role in breast cancer” after all.

But what does shaving have to do with it? Shaving removes more than just armpit hair. It also removes armpit skin; you end up shaving off the top skin layer. And, while there is very little aluminum absorption through intact skin, when you strip off the outer layer with a razor and then rub on an antiperspirant, you get a six-fold increase in aluminum absorption through the skin. Though this is good news for women who don’t shave, the high transdermal, or through-the-skin, aluminum uptake on shaved skin “should compel antiperspirant manufacturers to proceed with the utmost caution.”

Both European safety authorities and the U.S. Food and Drug Administration (FDA) specifically advise against using aluminum antiperspirants on damaged or broken skin. However, shaving before antiperspirant application “can create abrasions in the skin…thereby negating the specific warning by the FDA and EU.” (I’m sure everyone knows about the FDA’s cautionary advice, having read Title 21 Part 350 Subpart C50-5c1 of the Code of Federal Regulations.)

We get so much aluminum in our diet from processed foods—such as anticaking agents in pancake mix, melting agents in American cheese, meat binders, gravy thickeners, baking powder, and candy—that the contribution from underarm antiperspirants would presumably be minimal in comparison. “But everything was turned topsy-turvy in 2004,” when a case was reported of a woman with bone pain and fatigue suffering from aluminum toxicity. Within months of stopping the antiperspirant, which she had been applying daily to her regularly shaved armpits, her aluminum levels came down and her symptoms resolved. Although not everyone absorbs that much aluminum, the case “suggests that caution should be exercised when using aluminum-containing antiperspirants frequently.”

Recently, as you can see at 6:29 in my video, it was shown that women with breast cancer have twice the level of aluminum in their breasts compared with women without breast cancer, though this doesn’t prove cause and effect. Maybe the aluminum contributed to the cancer, or maybe the cancer contributed to the aluminum. Maybe tumors just absorb more aluminum. Subsequent research has suggested this alternative explanation is unlikely. So, where do we stand now?

The latest review on the subject concluded that as a consequence of the new data, given that aluminum can be toxic and we have no need for it, “reducing the concentration of this metal in antiperspirants is a matter of urgency.” Or, at the very least, the label should warn: “Do not use after shaving.” Of course, we could cease usage of aluminum-containing antiperspirants altogether, but then wouldn’t we smell? Ironically, antiperspirants can make us stink worse. They increase the types of bacteria that cause body odor. It’s like the story with antidepressant drugs, which can actually make one more depressed in the long run (as I discuss in my video Do Antidepressant Drugs Really Work?). The more we use antiperspirants, the more we may need them, which is awfully convenient for a billion-dollar industry.

What else can we do to decrease breast cancer risk? See, for example:

In health,

Michael Greger, M.D.

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