You Missed A Spot! Patchy Sunscreen Application Leaves Skin Vulnerable To Cancer

Enlarge this image toggle caption Olivia Sun/NPR Olivia Sun/NPR

You may not be thin-skinned, but your eyelids certainly are. The fragile tissue is the thinnest on the body, less than 1 millimeter thick.

While crepe-thin skin is great for blinking, it makes the area especially vulnerable to the sun's UV rays. Five to 10 percent of skin cancers occur on the eyelid.

Unfortunately, that same patch of sensitive skin is the area where we're most likely to skimp on sun protection, according to a study published Wednesday in PLOS One.

After providing 84 participants with a bottle of SPF-containing moisturizer and instructions to lather up, the team of British researchers turned their UV cameras on the subjects to see which areas of the face they missed. They found participants consistently missed their eyelids, skipping 20 percent of the region on average. When provided with sunscreen rather than moisturizer, people missed 14 percent of the area.

"People were applying cream [and] going out in the sun thinking they were protected," says Austin McCormick, lead author of the study. "And yet one of the most vulnerable areas was left unprotected."

Dermatologists say cancer-prone areas are often left neglected. Joshua Zeichner, a dermatologist and researcher at New York City's Mount Sinai Hospital, says he regularly sees patients forgetting to slap sunscreen on the sides of their neck and the tips of their ears — spots, he says, that are particularly sensitive to UV rays owing to the thinness of the skin.

The bottom lip, he says, is similarly at risk as few apply sunscreen there, yet it's slanted up toward the sun.

"In the office, we see sunburns in these areas, and we see skin cancers later in the life in these areas," says Zeichner. "People get lazy. It's not easy to be diligent."

McCormick says one possible reason people skimped on the eye area in particular is that participants wanted to avoid the stinging feeling that can occur when the lotion gets in your eyes.

But years as an eyelid surgeon at Liverpool's Aintree University Hospital have taught McCormick that the consequences of avoiding the area altogether can be just as painful — and much trickier to get rid of.

"One of the most common conditions I have to operate on is eyelid skin cancer," says McCormick. He says he has noticed many of the carcinomas he treats grow in places tricky to cover with sunscreen — the skin under the eyelashes and the patch at the inner corner of the eye that connects the upper and lower eyelid, called the medial canthus.

This was what originally gave McCormick the idea for his first study on sunscreen application in 2017. Using a similar method, the team of researchers found 3 in 4 people neglected the medial canthus when asked to apply sunscreen. The newest study found a similar percentage missing the region with SPF moisturizer.

Andrea Kossler, director of Oculoplastic Surgery and Orbital Oncology at Stanford University, says McCormick's findings match up with what she has found in her practice: Patients don't know they should be applying sunscreen on their lids.

"There's always this 'aha moment' where patients realize, 'Oh yes, I know I don't put my sunscreen there. I didn't think I was supposed to,' " she says.

But she insists that both moisturizer with SPF and sunscreen "can and should be placed right up to that eyelid margin." The Skin Cancer Foundation agrees.

While chemical sunscreens that protect the skin by converting UV rays to heat can sting, Kossler says physical sunscreens that block out the sun with minerals like zinc or titanium dioxide won't usually irritate the eyes.

Heading into the summer, she suggests people do double-duty with protection, pairing a physical blocker with sunglasses and a wide brim hat.