Moisturizers Up Skin Cancer in Mice
4 Commonly Used Moisturizing Creams Promote Tumors in UV-Exposed Mice
Testing Moisturizers for Safety
Dermatologist Keyvan Nouri, MD, director of dermatologic surgery at the University of Miami Miller School of Medicine and author of the best-selling book Skin Cancer, agrees that companies that make moisturizers should test their products.
"This study could definitely be a warning to alert these companies to consider testing moisturizing creams with some sort of assay," Nouri tells WebMD. "These creams need to be tested first before they come to market."
Moisturizers are classified as cosmetics by the FDA, which does not require that they undergo the same safety and efficacy tests required for drugs.
The moisturizers did not cause cancer in the mice. That came from their early-life radiation exposure. But the creams did make skin cancers grow faster and more readily.
Nouri notes that the radiation damaged the skin of the mice before the moisturizing creams were applied. That, he says, might account for the moisturizers' unusual tumor-promoting effect.
However, he notes that the skin cancers are becoming much more common in humans.
"There are over a million cases a year," he says. "It is by far the most common cancer we deal with. Skin cancers account for more than half of all cancers combined. But most skin cancers are totally curable."
What is it about the moisturizers that might promote cancer?
The Conney team asked Johnson & Johnson to make them a "custom blend" moisturizer without two ingredients previously linked to skin irritation (sodium lauryl sulfate) and tumor promotion (mineral oil). The custom blend (on which Rutgers University and Johnson & Johnson hold a patent) did not promote skin cancer.
But not all of the products tested use these ingredients, so exactly what -- if anything -- might be linked to cancer isn't known. And it's certainly clear that mouse and human skin are very different.
Moisturizers Still Necessary
Nouri warns consumers not to stop using moisturizers.
"As we get older, our skin gets drier," he says. "We need to moisturize, otherwise our skin gets dry and we get eczema, dermatitis, rashes, and so on. It is too soon to say from this study people should stop moisturizing."