Dr. Marianne Berwick Dr. Marianne Berwick

Three questions for skin cancer investigator Dr. Marianne Berwick

As Skin Cancer Awareness Month gets underway, melanoma expert says “enjoy the sun; just take precautions”

If you like to spend a lot of time outdoors, here are some statistics that might cast a shadow on your summer, according to the Skin Cancer Foundation:

  • Skin cancer is the most common form of cancer in the U.S. More than 3.5 million skin cancers in more than two million people are diagnosed annually.
  • Treatment of non- melanoma skin cancers increased by nearly 77 percent between 1992 and 2006.
  • Over the past three decades, more people have had skin cancer than all other cancers combined.

The University of New Mexico's Dr. Marianne Berwick has been on the front lines of melanoma and skin cancer research for nearly 30 years. She’s a firm believer in using team science to solve real medical problems – like skin cancer. In addition to her own melanoma investigations, Berwick is part of numerous international research collaborations in Australia, Canada, Italy and around the world.

May is Skin Cancer Awareness Month. So HSC Newsbeat asked Berwick to sit down and share some of her expertise in our risk of developing skin cancer in New Mexico, and how we all can reduce those risks.

HSC Newsbeat: How important to our health is sun exposure?

Berwick: Sun is good. It’s mood enhancing. Getting outside and exercising increases our endorphins and relaxes us in so many really positive ways. It also lowers our blood pressure. There’s a lot if benefit to being outdoors, and it’s very natural to want to be in the sun. What’s unnatural is when we’re indoors all week and then stay outdoors all weekend. This increasingly common lifestyle puts us at higher risk for skin cancer because of our skin’s intermittent exposure to the sun. This irregular exposure prevents our skin from adapting to the sun’s damaging UV rays. Interestingly, we find that people who have outdoor occupations are not at an increased risk for melanoma (which accounts for less than five percent of skin cancer cases, but results in the vast majority of skin cancer deaths).  So, if you are a farmer or work in any outdoor occupation – you can get melanoma – but your risk isn’t any higher.  

HSC Newsbeat: What are the short- and long-term risks of overexposure?

Berwick: Obviously, a sunburn can be unpleasant, but we’re more concerned with the long-term risks of DNA damage. An accumulation of damaged and unrepaired DNA can lead to different kinds of serious skin conditions. You can be at increased risk for squamous cell carcinoma (an uncontrolled growth of abnormal cells arising in the squamous cells of the skin’s upper layers). There’s a very direct link between overall long-term exposure to UV light and squamous cell carcinoma, because your risk goes up in a dose-response manner. The more sun exposure over your lifetime, the greater your risk.

It’s very different for melanoma. This intermittent sun exposure I referred to previously absolutely puts us at greater risk. But everybody’s at risk. So, we need to regularly examine our skin thoroughly, looking for spots, marks or lumps using the ABCDEs – asymmetry, border irregularity, color differentiation, large diameter, and evolving or growing.

People who are aware of their skin are much less at risk of dying from melanoma. The most common place for skin cancer to appear is on our backs. After that, for women it’s our legs, and for men it’s their head and neck. Understand that Melanoma can appear where the sun doesn’t shine, so check between your toes and under your feet; check your scalp, armpits and genital area. Some people have discovered melanoma under their hair. If you find any odd mark larger than a pencil eraser, you should see your primary care provider or dermatologist.

Along these lines, we are working on improving interventions with dermatologists, and even beauticians and massage therapists, who see people’s bodies and scalps all day every day. We’re also developing genetic screening for melanoma.

HSC Newsbeat: Who’s most at risk, and how can we lower those risks?

Berwick: We have very high UV levels across New Mexico all year long because of our altitude and latitude. There’s no time of year when we’re not at risk.

Let’s start with the easy stuff. When you’re outdoors, find shade. A lot of people in New Mexico wear hats, which is great. They give a lot of protection. I’m also seeing more people using umbrellas in the sun. Those are good, too. But I don’t think you need to buy UV-protection-treated clothing.

Sunscreens work well if you use them appropriately, or they can provide a false sense of protection if not. Sun protection factors, or SPFs, are a standardized measurement of effectiveness. Roughly, using an SPF 2, it takes twice as long to burn; using an SPF 15, it takes 15 times as long to burn. We recommend an SPF of 30, which gives 95-percent protection when used correctly. Anything above that is unnecessary for most people.

As a population, we don’t use enough sunscreen. Some of us don’t like it. Interestingly, people who use sunscreen incorrectly actually suffer more sun damage more often. To get the full benefit, apply sunscreen half an hour before going out and then half an hour after being out. It’s very important that you reapply every two hours or so while outside.

One important last thought. Please don’t go to tanning salons. Yes, they’re comfortable and you can get in and out quickly, but you get way more UV than you would from the sun. We’re finding more and more that tanning salons dramatically increase melanoma risk, especially in young people. These salons are banned in Australia for a reason. Protect yourself and enjoy the sun, but in moderation – like everything else.

Marianne Berwick, PhD, is a UNM School of Medicine Professor in the Division of Epidemiology and a full member of the Cancer Population Sciences Program.  Berwick earned her Doctoral Degree Environmental Epidemiology at Yale University in 1987. Her research focuses on Melanoma, DNA repair capacity and cancer disparities in New Mexico.


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