In 2002, Dana Mirick and colleagues at Fred Hutchinson Cancer Research Center (Seattle, Washington) published an epidemiological study that included questions on underarm shaving and deodorant use. The study compared 800 women with breast cancer with 800 randomly chosen women of similar age. That study found no link between underarm shaving, deodorant use, and breast cancer. Two new studies publicized on NewScientist.com suggest that the question may need further examination.
The first study, originally published in the Journal of Applied Toxicology (vol. 24, p.5), was led by molecular biologist Philippa Darbre at the University of Reading (United Kingdom). She and her colleagues found high concentrations of para-hydroxybenzoic acids (parabens) in 18 out of the 20 breast tumors that they examined. Other researchers have found that parabens bind to estrogen receptors and have estrogenic effects in yeast cells, animals, and in estrogen-sensitive human cells. Parabens are used as preservatives in cosmetics and some foods. The parabens found in the tumors had ester groups, indicating that they had been absorbed through the skin, not eaten and digested. Ester-bearing parabens mimic estrogen more strongly. Darbre asserts that the application of paraben-containing products to the underarm area may help explain why 60% of all breast tumors are located in the upper-outer quadrant, nearest the underarm, instead of being evenly distributed throughout the breast. Skeptics reply that the upper-outer quadrant has the largest amount of breast tissue. This study did not look at paraben concentrations in other areas of the breast or other body tissues.