Randolph's World

Can the use of antiperspirants and deodorants increase the risk for breast cancer?

Data from a study published online January 12 in the Journal of Applied Toxicology could relieve some of the fears about using underarm products, but could also raise questions and concerns.

The issue centers on exposure to alkyl esters of p-hydroxybenzoic acid (parabens), which are widely used as antimicrobial preservatives in pharmaceuticals, foods, and cosmetics. About 10 years ago, note the researchers, studies began to reveal that parabens had estrogenic properties, and estrogen plays a central role in the development, growth, and progression of breast cancer.

In this new study, researchers in the United Kingdom examined 160 breast-tissue samples obtained from 40 patients who had undergone a mastectomy for primary breast cancer. They found that 99% of samples had traces of at least 1 paraben, and that 60% had traces of 5 different parabens.

Importantly, 7 of the women reported never having used underarm products. This suggests that the parabens originated from another source, note the authors.

The source of the parabens measured in this and in previous studies cannot be identified; it is also not clear if the paraben traces come from long-term accumulation, current exposure, or a combination of both.

Parabens are only one part of a much bigger picture.
“I do think that the parabens are only one part of a much bigger picture,” said lead author Philippa D. Darbre, PhD, a reader in oncology at the University of Reading, United Kingdom.

“That is not to say that they do not contribute, but the issue is bigger,” she told Medscape Medical News. “Parabens are only one component…of personal care products. What is needed now is…a map of what chemicals there are in a human breast in the modern world and how they distribute across the breast, especially in relation to the site of the tumor.”

Adding to the Evidence

In their study, Dr. Darbre and colleagues found a disproportionate incidence of breast cancer in the upper outer quadrant of the breast. In all 40 women, levels of n-propylparaben were higher in the axilla region than in the mid or medial regions (Wilcoxon matched pairs test, P = .004 and P = .021, respectively).

This finding is not unusual; a number of studies over the past several decades have reported that a disproportionately high number of breast tumors in women originate in the upper outer quadrant of the breast, “for which a definitive explanation remains lacking,” the authors write. This disproportionality has been increasing in the United Kingdom, and now exceeds 50% of breast cancers.

“The detection of intact esters is more suggestive of a dermal route of exposure,” said Philip W. Harvey PhD, a registered toxicologist at Covance Laboratories Ltd, North Yorkshire, United Kingdom, who was not involved in the study. “Oral exposure results in the rapid conversion of the esters to the common metabolite p-hydroxybenzoic acid in both gut and liver. The skin has a much lower esterase capacity, which may explain the fact that 5 different intact paraben esters were found.”