Sun causes melanoma skin cancer. Sun protects you against melanoma skin cancer. Which is correct? Read on to find out.
Want to see your dermatologist’s head explode? The next time you see her or him, ask this question: “Does sun exposure cause melanoma?” This is a hot, controversial issue in dermatology right now. And I am going to answer it for you (and keep my head together).
Melanoma is cancer of your pigment cells. These pigment cells exist everywhere in your skin from your scalp to the bottom of your toes. When melanoma cells are concentrated into little nests, nevi or moles appear on your skin.
Part of the problem in answering the question is that there are different types of melanoma. For example, lentigo maligna is a melanoma that develops on severely sun damaged skin, usually on the head and face of older people. In contrast, acral melanomas occur on bottoms of the feet or on hands, often in young people with little or no sun exposure. Sun affects these two melanomas differently.
So Why Do We Think Melanoma is Caused by Sun Exposure?
- Ultraviolet light damages DNA in your skin.
- The rate of melanoma increases significantly when you look at people’s skin color from darkest to lightest — people with lighter skin, who always get sunburned, are much more likely to develop melanoma than people with dark skin who never get sunburned.
- The rate of melanoma changes when you look at where people live — the rate of melanoma is higher in places near the equator such as Hawaii as compared to Iowa, where the sun is less intense.
- An excellent study, called the Nurses Health Study, showed that the risk of getting melanoma was doubled if people had ever used a tanning booth.
What is the Evidence that Sun Does NOT Cause Melanoma?
- Ultraviolet light increases your vitamin D levels, which might protect you against some cancers.
- Many melanomas develop in areas with little or no sun exposure such as the buttocks or the bottom of the feet.
- In general, studies have not been able to show that wearing sunscreen protects you against melanoma.
- There is some evidence that a little sun exposure might actually protect you against melanoma.
- (OK, so now my head is throbbing).
Dr. Benabio’s Answer to the Question: Does Sun Exposure Cause Melanoma?
- It’s likely that sun exposure, particularly sunburns and extensive sun damage, increases your risk of developing certain melanomas.
- The chances that sun exposure increases your risk of melanoma depends a lot on you. Does your family have a history of melanoma? Do you have many “abnormal” or dysplastic nevi or moles? Do you live in a sunny climate such as Florida? Do you sunburn easily? If you answered “yes” to any of these questions, then you should be particularly cautious of excess sun exposure as your risk of melanoma might be high. Excess sun and sunburns would likely make your risk even higher.
- If you answered “no” to these questions, then some sun exposure (getting a little sun without getting sunburned) might not increase your risk of melanoma, and in some instances, could even lower your risk.
What Do I Often Advise My Patients?
- Take 1,000 IU of vitamin D each day. Then you never have to worry about getting sun to boost your vitamin D level.
- Enjoy life outdoors. Bike, run, surf, play, watch a ball game, hang out at the beach. However, especially in the summertime and if you have fair skin, wear a broad spectrum, SPF 30 sunscreen to prevent a sunburn (and to protect against other sun damage like wrinkles).
- Don’t lie out in the sun just to get dark (or to protect yourself from skin cancer).
- Don’t use tanning booths.
- In the long run, too much real or artificial sun exposure will not protect you and will increase your risk of wrinkles, basal cell carcinoma, squamous cell carcinoma, brown spots, white spots, “broken” blood vessels on your face and chest, and other sun damage.
I hope this helps.
Post written by Jeffrey Benabio, MD. You might also like:
Photo credit: Fdecomite, Flickr.com