A new report from a dermatology team at Kaiser Permanente health care centres in California has prompted me to reform. The team, headed by public health researcher Lisa Herrinton in Oakland, followed nearly half a million patients seen at the centres for up to 10 years. Half had already developed one or more actinic keratosis, a precancerous rough, scaly skin lesion caused by years of unprotected sun exposure.
As you might expect, these lesions most often form on the face, ears, back of the hands, forearms, scalp and neck and are — or should be — routinely removed when found by dermatologists to prevent progression to cancer. The lesions are markers of sun damage and can serve as an early warning system for people at risk of developing cancer somewhere on sun-exposed skin.
While the hazard is greatest for people with light skin, blue eyes, freckles or red hair, having a dark complexion is not a free pass. Tanning, not just burning, is a form of sun damage.
Among patients in the Kaiser Permanente study who were younger than 50, those with a diagnosis of actinic keratosis were nearly seven times more likely to develop a skin cancer called squamous cell carcinoma during the decade long follow-up. The cancer risk was eight times higher among patients older than 50 who had one or more actinic keratosis removed, and the more such lesions these patients had, the more likely they were to develop skin cancer during the follow-up.
Furthermore, the older the patient, the sooner cancer was diagnosed after actinic keratosis was found and presumably treated. It took seven to eight years for 10 per cent of patients in their 50s with an actinic keratosis to receive a diagnosis of skin cancer, but it took only three to four years for patients in their 70s and one to two years for those in their 80s.
Alas, those of us in the upper decades of life knew little in our younger years about the risks of sun damage beyond the need to avoid a bad sunburn. Many youngsters like me swam, hiked, biked and played sports minimally clothed while the sun tanned or burned our skin. We sunbathed coated in baby oil in a misguided effort to acquire a rich tan. And many of us, myself included, failed to reach adulthood with sun-protective habits that could have prevented the skin damage now woefully apparent.
Given that the risk of ultraviolet light to healthy skin has since been widely publicised, I'm astonished at how many people today visit tanning salons or use tanning beds at home, damaging the wholesome cutaneous barrier nature gave us.
Happily, the new study suggests that more people now have a greater understanding and respect for the sun's effects on skin and can look forward to a healthier future, said Dr. Sangeeta Marwaha, a dermatologist in Sacramento, California, and co-author of the study. Among people who entered the study in 2018, the risk of developing skin cancer was two-thirds that of study entrants in 2008 who were followed for an equal number of years.
"There's been an increase in sun-protective habits and a resulting decrease in the development of skin cancer," Marwaha said in an interview. "Parents today are more likely to protect their children from undue sun exposure, and the use of sunscreen is now more mainstream."
But there's still a long way to go. Fostering a healthy respect for sun protection in young children is especially important because experts estimate that 80 per cent of a person's lifetime sun exposure is acquired before age 18.
Repeated exposure to the sun's ultraviolet radiation causes most of the skin changes — wrinkles, age spots and tiny broken blood vessels — generally considered a normal result of aging. Yes, aging plays a role, but these effects occur much earlier in life on sun-exposed skin. UV light damages the elastin fibres in skin, causing it to stretch, sag and wrinkle. It also damages surface blood vessels, rendering them more fragile and easily bruised.
And Zachary W. Lipsky, a biomedical engineer at Binghamton University, found that UV radiation weakens the bonds that help the cells in the top layer of skin stick together, damaging the skin's structural integrity and leaving it more vulnerable to infection.
But while some of these effects can be masked by cosmetic treatments and plastic surgery, the most serious damage done by UV radiation — to the DNA of skin cells — is permanent and irreversible and can result in cancer-causing mutations.
Furthermore, preventing sun damage is easier and cheaper than reversing it and less likely to result in premature wrinkles and scars. Try to schedule your outdoor activities early or late in the day, avoiding the peak sun hours of 10am to 4pm.
Routinely apply a broad-spectrum sunscreen with an SPF of 30 or higher to exposed skin year-round even on cloudy days, using at least a quarter teaspoon on your face alone. Apply sunscreen half an hour before going out and reapply it every two hours and after being in the water. Modern sunscreens are not greasy or pasty, but they lose effectiveness with time so be sure to check the expiration date. Even if you sit under an umbrella at the beach or in the park, the sun's reflected rays will hit your skin.
Wear a hat with a wide brim, especially important for men who are balding. If you have the means, invest in top-quality sunglasses and clothing, including swimwear, with built-in SPF protection. The darker and heavier the fabric, the better. "A plain white T-shirt has an SPF of 4, whereas dark blue denim jeans could have an SPF of 2000," Marwaha said.
This summer I plan to apply sunscreen daily and wear a long-sleeved sun-protective shirt when I walk, cycle and garden, even on cloudy days, a habit I wish I'd cultivated decades ago.
Written by: Jane E. Brody
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