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How Well Do Sunscreens Work to Prevent Skin Cancer?

If you follow your dermatologist's recommendation, you do NOT go out in the sun without sunscreen. But how good is the evidence that sunscreens prevent skin cancer?
How Well Do Sunscreens Work to Prevent Skin Cancer?
Child kid sun sunburn beach vacation

We have all been told countless times to smear on the sunscreen! The Australians even had a slogan: “Slip! Slop! Slap!” It was part of a 1981 health campaign to: “Slip on a shirt, slop on sunscreen and slap on a hat” to “stop skin cancer.” There is little doubt that sun exposure, especially in Australia, contributes to a lot of skin cancer. But do sunscreens prevent skin cancer? It’s more complicated that you might think, as this reader suggests:

What About Vitamin D?

Q. It seems to me that sunscreens may prevent burning, but I’m not sure they prevent skin cancer. The incidence of all types of skin cancer has increased since sunscreens were introduced.

I also worry that people who shun the sun completely may be missing out on vitamin D. I’ve read that this vitamin helps keep cancers (even skin cancers) from developing. Can you help with this puzzle?

The Research On Sunscreens is Confusing:

A. Consistent sunscreen use is a pillar of public health campaigns for preventing skin cancer. To answer this reader’s concerns we went searching for gold-plated evidence to support sunscreen effectiveness to prevent skin cancer. We were surprised at what we found.

Let’s Search Cochrane!

One of our first search destinations was the Cochrane Collaboration. We rely on this independent organization to evaluate a range of health strategies. Here is how the scientists describe their work:

“The main purpose of The Cochrane Collaboration is to develop systematic reviews of the strongest evidence available about healthcare interventions. Consumers and health practitioners can then work together to make the best possible decisions about health care. The reviews are published electronically within The Cochrane Library and are freely accessible in shortened versions (abstracts and consumer summaries).”

Cochrane and Sunscreens to Prevent Skin Cancer:

What we found about sunscreens to prevent skin cancer was surprisingly skimpy (Cochrane Database of Systematic Reviews, July 25, 2016).

The authors concluded:

“In this review, we assessed the effect of solar protection in preventing the occurrence of new cases of keratinocyte cancer. We only found one study that was suitable for inclusion. This was a study of sunscreens, so we were unable to assess any other forms of sun protection. The study addressed our prespecified primary outcomes, but not most of our secondary outcomes. We were unable to demonstrate from the available evidence whether sunscreen was effective for the prevention of basal cell carcinoma (BCC) or cutaneous squamous cell carcinoma (cSCC).”

What About Sunscreen to Prevent Melanoma?

The Cochrane analysis did not address the value of sunscreens to protect the skin against melanoma, the most serious form of skin cancer. So we went searching further.

We found a meta-analysis of 29 studies published in the European Journal of Dermatology (April 1, 2018).  The journal article was titled:

“Use of sunscreen and risk of melanoma and non-melanoma skin cancer: a systematic review and meta-analysis”

To our amazement this review did not show sunscreen protected people against skin cancer. The authors wrote:

“The use of sunscreen is a key component of public health campaigns for skin cancer prevention, but epidemiological studies have raised doubts on its effectiveness in the general population. This systematic review and meta-analysis aimed to assess the association between risk of skin cancer and sunscreen use.

“The cumulative evidence before the 1980s showed a relatively strong positive association between melanoma and sunscreen use (cumulative OR [odds ratio]: 2.35; 95% CI: 1.66-3.33). The strength of the association between risk of skin cancer and sunscreen use has constantly decreased since the early 1980s, and the association was no longer statistically significant from the early 1990s. While the current evidence suggests no increased risk of skin cancer related to sunscreen use, this systematic review does not confirm the expected protective benefits of sunscreen against skin cancer in the general population.”

The Man Just Bit the Dog!

This isn’t the way it is supposed to work. We would have expected a significant inverse association–the more sunscreen used, the less skin cancer.

Other Research Reviews?

One analysis does not resolve the question whether sunscreen can prevent skin cancer, even if it included 29 studies. So we went looking for other reviews. A journal that most physicians admire is the Annals of Internal Medicine. A study published on December 16, 2003 analyzed 18 studies. It was titled:

“Sunscreen use and the risk for melanoma: a quantitative review”

The authors reported:

BACKGROUND:

Originally developed to protect against sunburn, sunscreen has been assumed to prevent skin cancer. However, conflicting reports include claims that sunscreen increases risk for melanoma.

OBJECTIVE:

To examine the strength and consistency of associations between melanoma and sunscreen use in the published literature.

CONCLUSIONS:

No association was seen between melanoma and sunscreen use. Failure to control for confounding factors may explain previous reports of positive associations linking melanoma to sunscreen use. In addition, it may take decades to detect a protective association between melanoma and use of the newer formulations of sunscreens.”

It was a relief to read that the authors concluded that sunscreen use did not cause melanoma. But it was disappointing to see that they could not conclude that sunscreen could prevent skin cancer. Their last sentence, though, is very revealing. “It may take decades to detect a protective association between melanoma and use of the new formulations of sunscreens.”

Really? It has been decades since high SPF sunscreens have become available. They do a great job preventing sunburns. How is it possible that we do not have fabulous research proving that sunscreens prevent skin cancer?

We do not get it. Where’s the FDA? How come dermatologists haven’t conducted huge studies supporting their recommendations to smear on the sunscreen? Why hasn’t the NIH funded such research? Why don’t we have an answer to the question?:

Why Is Skin Cancer Going Up Despite Such Effective Sunscreens?

What Should We Do? A People’s Pharmacy Perspective:

It still makes sense to protect yourself from sunburn, which is painful as well as dangerous. Perhaps you have heard the phrase:

“Only mad dogs and Englishmen go out in the noonday sun.”

It has been attributed to an Indian proverb, Rudyard Kipling and more definitively to the songwriter, Noel Coward. He did write a song titled “Mad Dogs and Englishmen.”

Should you wish to listen to the song and read all the lyrics, here is a link to

“Mad Dogs and Englishmen”

We would go further than Noel Coward. We encourage people to stay out of direct sunlight between 10:00 am and 2:00 pm. If you do go out, follow the Australian admonition to slip on a shirt with long sleeves and slap on a protective hat. There is also specialty clothing and swimwear that provides some ultraviolet protection. Just search for sun protective clothing.

What About Sunscreen and Vitamin D?

Our reader asked a question about sunscreen and vitamin D. Sunscreen does prevent vitamin D formation in the skin. People who protect themselves from UV rays may not make adequate amounts of vitamin D. Oral supplements might be helpful.

Should you wish to find a sunscreen without oxybenzone, a suspected endocrine disruptor, you may wish to read this article:

Can You Find A Good Sunscreen Without Oxybenzone?

Share your own thoughts on sunscreen to prevent skin cancer below in the comment section. We would love to hear from dermatologists. We live in an era of evidence-based medicine. Why don’t we have really strong evidence that sunscreens prevent skin cancer? Without that research how can dermatologists be so sure that their advice is based on solid scientific evidence?

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.” .
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