WHAT IT MEANS: Conclusive research that shows whether sunscreens do actually prevent melanoma will likely never materialize. There are just too many factors to control for, says Berwick. Including, as mentioned, behavioral factors. "There's a fair amount of data suggesting that sunscreen is used most often by people already at risk for melanoma, or by people who are going to go out and stay outside for long time." Those people also don't reapply it properly, she adds, and when they're asked by researchers about their habits, their recollections can be inaccurate.
That means, Berwick says, that we're pouring money into products that may or may not be giving us the protection we expect, while ignoring truly effective sun-protection strategies. Effective or not, sunscreens are so heavily marketed that the public often assumes that they should be our first line of defense against sun damage and the various forms of skin cancer. "Surveys show that more than anything, people rely on sunscreen," says Glanz. "And I do think that that needs to change." Berwick agrees. "Everyone wants to think that there's a magic bullet, or if they just use sunscreen, they can prevent cancer," she says. "And the industry has made a ton of money promulgating this idea."
And people may not be able to rely on dermatologists to help, as they tend to succumb to the inherent problem other doctors face, Glanz says. "People don't get enough time with the doctor, and the doctor doesn't spend as much time counseling and giving advice as is necessary to convince and even educate people about proper protection," she says, like seeking out shade and covering up with hats, long sleeves, and long pants.
Those measures protect everyone against the known cause of melanoma, which is intermittent sun exposure (like that experienced by people who work in offices all day and spend their weekends outdoors). "Seventy-five percent of melanoma cases occur on relatively unexposed sites, like your back or your trunk, which gives support to idea of intermittent sun exposure," Berwick says. Women get more melanomas on their legs and men get it on their backs, she adds, which see more sunlight when you're wearing casual weekend clothing. That may be because our bodies haven't built up adequate defense mechanisms. Studies on people who spend all day working outside, for instance construction workers, show no higher risk of melanoma or squamous or basal cell carcinomas than the general population. "It may be that their bodies develop a natural defense mechanism," Berwick says. "Their skin gets a little thicker and there may be DNA-repair capacity that's built up by continuous sun exposure."
This summer, as you head out to get your weekend intermittent sun exposure, take truly effective precautions against sun damage:
• Dress defensively. What you wear matters. "My first line of defense is a hat and long sleeves and long pants," Berwick says. And despite what the sunscreen makers may say, the Centers for Disease Control and Prevention, the American Cancer Society, and the International Agency for Research on Cancer all agree with Berwick. If you feel like you'd smother in long sleeves on a 100-degree day, look for special sun-protection clothing that's woven in a way that allows the material to breathe and keep you cool while blocking UVA and UVB rays. Another benefit? Hats and parasols keep you from sweating, so there's no risk of sunscreen sliding off your face into your eyes and causing them to sting or burn. Plus, once you've got your clothes on, there's no need to reapply them!
• Select sunscreen carefully. Beyond the fact that they may or may not work, sunscreens can contain harmful active ingredients. Some sunscreens work by employing chemical UV blockers, such as benzophenone or octinoxate, that act as hormone disruptors and exhibit estrogenic activity. Other products utilize physical UV blockers, such as zinc oxide and titanium dioxide, that lay on top of your skin to prevent UV rays from doing any damage. Those blockers can make your skin white, though, so some companies turn them into sunscreen nanoparticles that are so small, they disappear when applied. Nanoparticles can bypass the skin and cause cell and tissue damage, and may cause cancer. Finally, retinol A, added to improve your skin's appearance and sometimes used as a sunscreen preservative, has been shown in animal studies to promote tumor growth.
Check the labels before you buy. Consult the Environmental Working Group's annual sunscreen guide to find products free of these ingredients for those occasions when you can't escape sun exposure.
• Do regular skin checks. "My second line of defense is to put on sunscreen to prevent sunburn, and third, I take a peek at my skin," Berwick says. "People who are aware of their skin for cosmetic reasons halve their risk of dying from melanoma." Keep an eye out for moles that change color or are irregularly shaped, and help your spouse out. Studies have shown that melanoma is more common in men over 50, and older men are more likely to die from the disease than women, Berwick says. Men often don't pay attention to their skin or know the warning signs of melanoma, she adds, and they need an extra push. Backs and scalps are particularly susceptible, since those areas are hard to see.