Antiperspirant, cancer link a myth

A few years back we got my in-laws hooked up to the Internet so they couldsend e-mail to their friends and family and surf the Web. Mostly, my father-in-law uses it to forward jokes my way and to pass along pieces of medical news I might be interested in.

The latest was a dire warning about antiperspirants and breast cancer. The writer of the e-mail claimed that doctors “knew” that antiperspirants “caused” breast cancer.

As I read on, the wacky explanation looked increasingly familiar. I had read this exact e-mail before. It was complete medical fiction.

So I did a Google search for “antiperspirants and breast cancer.” (Have I mentioned how much I love the Internet?) And there I discovered a marvelous site: www.snopes.com – The Urban Legends Reference Pages. That’s right: It’s an urban legend.

Snopes.com is dedicated to researching urban legends. Barbara and David Mikkelson maintain the site and do most of the research, looking for the truth in the story.

This one has been circulating around the Web since the early ‘90s, and it’s a myth.

Until recently, there was nothing in our medical literature that addressed the association between antiperspirants and breast cancer. But in response to the persistent rumors that would not disappear off our beloved Internet, researchers at the Fred Hutchinson Cancer Research Center set out to see if any such association existed.

They were in the process of designing a questionnaire looking at environmental exposure to various agents (light exposure in night shift workers, magnetic field exposure) when they became aware of the antiperspirant concern. So they added that to the questionnaire.

This was a well-designed study with a breast cancer group (813 cancer patients) and a control group (793 who did not have cancer). They interviewed each of the study participants.

They found no difference in antiperspirant use in the two groups.

Two more studies have come out since that Fred Hutch study, and both claim an association between breast cancer and antiperspirant use. So I looked at these studies to see how they were done.

The first study claimed that women who used antiperspirants within an hour of shaving were diagnosed at an earlier age. But this study sent out more than 1300 questionnaires and received only 437 back. There was no control group to compare with.

And researchers know that studies like this are subject to what is called “recall bias.” Could it be that more women who shaved and sprayed returned the questionnaires? Could it be that women with cancer would be searching for a cause and that would bias their answer?

In the next study, researchers in Edinburgh looked for the presence of parabens, a common preservative in cosmetics and food, in breast cancer tumor tissue. They found traces present in 18 out of 20 tumors studied.

Well, that’s scary, I guess, but they didn’t look at normal tissues either in the breast or in other body tissues. And they didn’t study the tissues of women who didn’t have breast cancer.

Were there parabens in those tissues as well?

As we say, more studies are necessary, but a well-conducted study trumps two poorly conducted ones any time.

Breast cancer is a scary disease. We would all like to find one “cause” that we could eliminate.

But it’s not going to be that easy. Breast cancer, like most cancers, comes about because of an intricate interplay of genetic and environmental factors.

Risks like current age, family history, a personal history of breast cancer, age when your period started and age when your first child was born (or never having had children) all contribute to an increased risk of breast cancer. But no one knows of a “cause.”

So if you’re lucky enough to get one of these e-mails with unsubstantiated claims about the cause of this or that disease, check it out at swnopes.com. I’ve already bookmarked the site.