How to protect your skin from sun damage and cancer

correction A previous version of this article incorrectly said that skin cancer is diagnosed in 20 percent of Americans each year. It should have said that skin cancer is diagnosed in 20 percent of Americans in their lifetime. The article has been corrected. Your skin does a lot for you. The body’s largest organ has three main layers — epidermis, dermis and hypodermis — and creates a barrier against potentially harmful substances while also helping to regulate your body’s temperature. It’s out there every day fighting for your health. But strong as it is, your skin is also susceptible to damage, particularly from the sun, which the 20 percent of Americans diagnosed with skin cancer in their lifetime know all too well. Skin damage can take years to appear, but it can be quite deadly.

“No matter what age you are, no matter what your level of sun damage is, it’s never too late to take care of your skin. Start protecting it now,” said Catherine Pisano, Mohs micrographic surgeon and cutaneous oncologist at Harvard Medical School.

Here’s what experts had to say about protecting your skin this summer:

How common is sun damage?

“Extremely common,” said Mary L. Stevenson, an associate professor in the Ronald O. Perelman Department of Dermatology at NYU Grossman School of Medicine. “Two different ranges of light wavelengths cause different forms of skin damage.”

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Ultraviolet A (UVA) leads to more premature aging of the skin, but ultraviolet B (UVB) can cause “DNA damage that turns normal cells into precancerous or cancerous cells,” Pisano said. Because “damage can take years to show up,” sunburns you got in your 20s could become skin cancer in your 50s.

The environment may be assaulting our skin, as well, said Shadi Kourosh, an associate professor of dermatology at Harvard Medical School.

“We are increasingly learning about the role of other factors, such as visible light, infrared (heat) radiation and pollution as contributors to skin cancer,” Kourosh said. “ … There is evidence that airborne pollutants due to smog and wildfires can actually corrode the skin barrier and cause DNA damage.”

How common is skin cancer?

There are 9,500 cases of skin cancer diagnosed daily in the United States, making it the most common cancer in the country, according to the American Academy of Dermatology.

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“Basal cell carcinoma is most common, followed by squamous cell carcinoma and melanoma,” Stevenson said. More than 8,000 people in the United States are expected to die of melanoma this year, according to the American Cancer Society.

Squamous and basal cell cancers occur in the outermost layer of the skin, while melanoma originates in cells known as melanocytes, which can cross into the deepest layers of the skin, making it the most deadly.

“Basal cell carcinoma’s five-year survival approaches 100 percent,” said Stacy P. Salob, clinical assistant professor at Weill Cornell Medical College. “However, if a basal cell carcinoma is left untreated, it can grow and ulcerate — which could be painful, get infected, and destroy nerves, fascia or cartilage. Squamous cell carcinoma is also curable if caught early. Only about 2 percent of cases metastasize, but that’s when it becomes dangerous. Then the five-year survival rate is 40 percent.

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“If it’s caught early, the five-year survival rate for melanoma is more than 99 percent. But if it reaches the lymph nodes, according to the Skin Cancer Foundation, only 74 percent of patients survive, and if it metastasizes to another organ, the survival rate drops to 35 percent.”

How do you prevent skin cancer?

“You can’t really eliminate the risk of skin cancer,” said Jeremy Brauer, clinical associate professor of dermatology at NYU Langone Health. “But you can reduce your risk by practicing sun protective behaviors. These include appropriate application of UVA/UVB broad spectrum sunscreen, wearing [ultraviolet protection factor] clothing, including hats and sunglasses, seeking shade and scheduling outdoor activities before 10 a.m. or after 4 p.m. whenever possible.”

“Employing more sun protective behaviors now is super-effective in diminishing the sun damage that you already have, as well as preventing more sun damage,” Pisano said.

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In a recent study, the Environmental Working Group, a nonprofit advocacy and research organization, said only 25 percent of sunscreens on the market met the group’s standards for safety and effectiveness. The organization also released a list of best sunscreens, all of which have titanium dioxide and zinc oxide, making them “mineral” sunscreens.

Tell me about sunscreens available in Europe and Asia but not the United States.

“We have relatively few ingredients available in the U.S. that block UVA rays. Europe and Asia have a number of excellent ingredients that are effective UVA blockers,” Salob said, though she added that many U.S. sunscreens work well.

In the United States, the Food and Drug Administration regulates sunscreens as nonprescription drugs, a lengthy process. Bemotrizinol, a broad-spectrum UV filter ingredient found in many European and Asian sunscreens, is among the sunscreen ingredients awaiting FDA approval for sale in the American market.

Are there any new treatments for people with sun-damaged skin? What are their side effects, and when are they used?

People with a history of multiple skin cancers or precancerous lesions called actinic keratoses may be prescribed topical creams (like fluorouracil, often combined with calcipotriene) that help to treat and reduce precancerous cells or photodynamic therapy (PDT), Stevenson said. PDT involves a solution that is applied to the skin and then light-activated.

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“The treatments create a robust immune system response to the DNA damage and lower the risk of getting skin cancer from these damaged cells. Neither is a ‘one-and-done’ treatment.” Pisano said. “You’ll probably have to do it about once a year as a maintenance therapy. Fluorouracil is applied at home and PDT [is] an in-office treatment, so the patient may decide which is better for them.”

While these treatments are FDA-approved for precancerous spots (also called solar keratoses), Salob said they are also sometimes used to treat “superficial skin cancers. Imiquimod, another topical, is FDA-approved for basal cell carcinomas as well as solar keratoses. It stimulates the immune system to treat the area affected with skin cancer.”

A laser treatment known as fractional resurfacing (or Fraxel) can reduce precancerous changes and decrease the risk of developing certain cancers.

With these new treatments, can people feel confident that they can dodge the skin cancer bullet?

The treatments help, but they’re not enough. “You can still get skin cancer, even with these treatments. So, it’s important to get regular skin checks with a board-certified dermatologist,” Pisano said.

When should you see a doctor about something on your skin?

“Any sort of pimple, bug bite or red bump that does not go away within four to six weeks, and anything that is itchy, painful, bleeding, or increasing in size should be shown to a dermatologist,” Pisano said.

The ABCDEs of melanoma

The American Academy of Dermatology recommends the ABCDE Method to help spot possible melanoma, the most deadly form of skin cancer. Here are things to look out for:

Asymmetry: One half of a spot on the skin doesn’t match the other half.

Border: Its border isn’t smooth, but rather jagged and irregular.

Color: A spot’s color is uneven, with shades of brown, black, gray, red or white.

Diameter: A spot on the skin is larger than the tip of a pencil eraser (6 mm).