2012 update: The analysis below does not take account of the most recently published study, in which researchers found traces of parabens, a class of preservatives commonly found in cosmetics (including deodorants), in breast tissue samples from mastectomy patients. The study says the evidence does not confirm a link between parabens and breast cancer, but does call for further research to determine whether there is one.
• Read more: Parabens and Breast Cancer Controversy Continues
CBS News published a story in Dec. 2005 citing a 2003 study which found a statistical link between the incidence of breast cancer in young women and the use of antiperspirants combined with frequent underarm shaving. "I personally feel there is a very strong correlation between the underarm hygiene habits and breast cancer," said immunologist Dr. Kris McGrath, the author of the study.
The CBS story included a statement from the FDA in which officials seemed to back off slightly from their previous insistence that the correlation is nothing but a myth:
FDA is aware of concerns that antiperspirant use (in conjunction with underarm shaving) may be associated with increased risk of developing breast cancer. FDA continues to search scientific literature for studies examining this possible adverse drug effect. Unfortunately, there are many publications that discuss the issue, but very few studies in which data has been collected and analyzed. Overall, the studies (containing data) are inconclusive in determining whether antiperspirants, in any way, contribute to the development of breast cancer. FDA hopes that definitive studies exploring breast cancer incidence and antiperspirant use will be conducted in the near future.
Although a 2002 study in the Journal of the National Cancer Institute found no evidence whatsoever to support the claim that using antiperspirants or deodorants increases a woman's risk of breast cancer, another study published in 2003 found a statistical link between underarm shaving combined with the frequent use of antiperspirants and an earlier age of breast cancer diagnosis. Researchers said it was unclear, however, precisely which of these factors shaving or antiperspirant use, or both was operative in their results, and that further investigation is required.
Yet another 2003 study found traces of parabens, a class of preservatives used in the manufacture of many cosmetic products including antiperspirants, in tumor samples taken from breast cancer patients. "While there is no evidence they cause cancer," a BBC News article about the study said, "the scientists have called for the use of parabens to be reviewed." Though parabens have a "very, very good safety profile," according to a representative of the cosmetics industry, researchers insist there may be cause for concern because parabens have been shown in other studies to mimic the action of estrogen, a known factor in the etiology of breast tumors.
As of January 2004, bodies such as the American Cancer Society and National Cancer Institute continued to maintain that the evidence is inadequate to conclude that any causal link between antiperspirant use and breast cancer exists.
1999 analysis: One of the more persistent medical misconceptions still striking fear into the hearts of Internet gossipers is the claim that the use of underarm antiperspirants or deodorants is "the leading cause of breast cancer" (see full text of email rumor).
The scare story has been thoroughly trounced by reliable sources, including the American Cancer Society. According to researchers, antiperspirants have no known (or even suspected) connection with breast cancer. It goes without saying they are not its "leading cause."
In a May 1999 article by Dawn MacKeen on Salon.com, Dr. Mervyn Elgart of the department of dermatology at George Washington University eloquently dismissed the rumor as, and I quote, "a bunch of crap." Other experts have expressed similar views, though not necessarily in those words.
Email users take note: before you believe or forward any supposed "medical information" you receive in your inbox, check with your personal physician or other reliable source to find out if it's really true. Experience shows that nine times out of ten, it's not.