Burning Questions

Research Blogging / by Dave Munger /

Contrary to a handful of recent media reports, in the battle against skin cancer, sunscreen is still beneficial, and sunburns and tanning salons are the key enemies.

Credit: Flickr user Whatsername?

Two weeks ago, like millions of others this year, I went under the knife of a plastic surgeon. No, I wasn’t getting a facelift or a tummy-tuck, I was getting three precancerous moles removed from my back (my physician had recommended a plastic surgeon for the procedure to minimize scarring). I had an early form of skin cancer, probably as a result of getting sunburned during my childhood. Although in most cases skin cancer is easily treated, in the US in 2006, 8,441 people died of skin melanoma, the deadliest form of skin cancer. According to the American Cancer Society, more people in the US will die from skin cancer in 2010 than from stomach cancer.

Even in relatively benign cases like mine, it’s still rather dramatic having a surgeon carve a 4-centimeter chunk of flesh out of your back, and there’s always the potential that the cancer will recur and require even more invasive procedures. Needless to say, I’ve become quite interested in what I can do to prevent skin cancer in the future.

One issue I’ve seen in the news is whether sunscreen actually does much good in preventing skin cancer. Scott Gavura, a pharmacist who blogs at both Science-Based Pharmacy and Science-Based Medicine, took up the issue last week. He says that some news outlets have suggested that some ingredients in sunscreens might cause cancer.

Weighing the evidence, Gavura sides in favor of sunscreens, particularly those that block both UVA and UVB radiation. However, two ingredients in particular have indeed raised some concerns. Some sunscreen products contain retinyl palmitate (vitamin A), which is marketed as an anti-aging product. The problem is that vitamin A has been shown to cause cancer in laboratory mice because it’s a photoenhancer; it actually increases the effect of UV radiation on the skin. But the key study on vitamin A in sunscreens hasn’t been completed, so while we know that vitamin A is damaging on its own, we can’t say on balance what the effect of using sunscreen with vitamin A is. Clearly it would be better to avoid sunscreens that contain retinyl palmitate, just in case.

Similarly, the Environmental Working Group, an environmental advocacy organization, also recommends against sunscreens with oxybenzone, because oxybenzone may disrupt human hormones. A quick check of my own “dermatologist-recommended” sunscreen for oxybenzone shows that it contains 6 percent of the stuff! Gavura again says the research on health effects of oxybenzone at the levels found in sunscreens is inconclusive, but since many effective sunscreens don’t contain oxybenzone, it’s sensible to avoid those that do.

While it’s best to avoid getting too much sun, wearing sunscreen while outdoors is clearly preferable to wearing none. Both the American Cancer Society and Cancer Research UK have good informational pages on how to minimize your chances of getting skin cancer.

But what if you don’t get burned, building up a perfect bronze in a tanning salon? Surely that can’t cause cancer, can it? Um, yes it can, according to Cancer Research UK. A 2006 review of the research found an increased risk of melanoma in people who used sunbeds before age 35, but that study was criticized because it couldn’t show whether more use of sunbeds was associated with a higher risk of cancer. Now a new study fills that gap. The research, led by DeAnn Lazovic and published this month in Cancer Epidemiology, Biomarkers & Prevention, found that among heavy users of tanning beds, the more they used them, the higher their risk of melanoma. Even users who had never been burned on a sunbed had a significantly higher cancer risk than those who had never used one. Burning—a common occurrence even in the controlled environment of a tanning salon—more than doubled the risk of cancer.

As a child growing up in rainy Seattle, I didn’t get much sun. I think I can trace the origins of my brush with cancer to a single trip to Hawaii when I was ten years old. Now, raising fair-skinned children in North Carolina, my wife and I have seen our kids endure taunting over their parents’ insistence on sunscreen. We can only hope they’ll thank us years from now ... if they’ve managed to avoid the most-diagnosed form of cancer in America.

Dave Munger is editor of ResearchBlogging.org, where you can find thousands of blog posts on this and myriad other topics. Each week, he writes about recent posts on peer-reviewed research from across the blogosphere. See previous Research Blogging columns »

 

Originally published June 16, 2010

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