ActinicKeratosesNet Article
It’s Never Too Late for Sun Protection

Dermatologists are frequently asked by their patients who have actinic keratoses (AKs), “Doctor, why do you want me to start protecting my skin from the sun now? Hasn’t the damage already been done?”

While it is true that AKs develop on skin that has significant sun damage, twenty-plus years of research shows that sun protection can be beneficial after the skin is damaged by unprotected exposure to ultraviolet (UV) light. These studies indicate that sun protection may:

• Prevent further damage

• Allow the skin to repair some of the existing damage

Since a person with AKs is always considered at risk for developing new lesions and any single lesion has the potential to progress to squamous cell carcinoma, a type of skin cancer that can be deadly, the findings are certainly encouraging. Studies indicate that sun protection may inhibit p53 gene mutations - mutations that contribute to the development of skin cancer in humans and mice. Gene p53 acts as a tumor suppressor; however, repeated UV exposure causes p53 to mutate - stifling its tumor-suppressing abilities. These mutations begin long before skin cancer develops because p53 mutations are found in AKs and sun-damaged skin. In a scientifically controlled study, sun protection reduced p53 mutations by 88% to 92%, implying that sun protection may inhibit the development of skin cancer.

More compelling evidence for practicing sun protection after signs of damage are visible comes from dermatologic research that shows skin can repair some of the UV damage when protected from further exposure. One study indicates that damage to the dermis - middle layers of skin that contain collagen and elastin - was partially repaired when protected, even with continued UV exposure. Another study found that destruction and repair occur simultaneously with continued UV exposure. However, the more UV exposure received, the more destruction outpaces repair. This study also found that when UV exposure ceases, both the outer and middle layers of skin can repair some of the damage. Given this finding, researchers concluded that while sun protection should begin early in life, mature adults who have sun-damaged skin should adopt protective measures.

Sun Protection: More than Occasional Sunscreen Use
Sunscreen use is only part of a comprehensive sun-protection plan. In addition to daily application of a broad spectrum (protects against both UVA and UVB rays) sunscreen that has a Sun Protection Factor (SPF) of 30 or more, the American Academy of Dermatology recommends:

1. Avoid deliberate tanning. Ultraviolet light from the sun and tanning beds causes skin cancer and wrinkling. If you want to look like you’ve been in the sun, consider using a sunless self-tanning product. When using a self-tanning product, you should continue to use sunscreen.

2. Get vitamin D safely through a healthy diet that includes vitamin supplements. Don’t seek the sun.

3. Generously apply sunscreen to all exposed skin. Before going outdoors, generously apply a sunscreen that has a Sun Protection Factor (SPF) of at least 30 and is broad-spectrum — protects against both ultraviolet (UVA) and ultraviolet B (UVB) rays. While outdoors, re-apply the sunscreen approximately every two hours, even on cloudy days, and after swimming or perspiring.

4. Cover up when you must be in the sun. Wear long sleeves, pants, a wide-brimmed hat, and sunglasses that protect against both UVA and UVB rays.

   • Clothing protects your skin from the sun’s harmful rays. The tighter the weave, the more sun protection provided. In fact, clothing plays such an important role in sun protection that clothing designed specifically to protect against the sun as well as laundry additives created to boost clothing’s protective function are available. Your dermatologist may be able to provide you with more information about these products.

   • A wide-brimmed hat shades your face and neck from the sun’s rays. Wide-brimmed means the brim circles the entire hat and shades the face and neck.

5. Use extra caution near water, snow, and sand. These reflect the damaging rays of the sun, which can increase your chance of sunburn.

The next time your dermatologist brings up sun protection why not surprise your doctor by mentioning that you know how important sun protection can be for a patient with AKs. You may even want to ask for sunscreen recommendations as the choices can be overwhelming.

References:
Ananthaswamy HN et al. Inhibition of UV-induced p53 mutations by sunscreens: implications for skin cancer prevention. J Investig Dermatol Symp Proc. 1998 Aug;3(1):52-6.

Kligman LH. Connective tissue photodamage in the hairless mouse is partially reversible. J Invest Dermatol. 1987 Mar;88(3 Suppl):12s-17s. 

Kligman LH. Photoaging. Manifestations, prevention, and treatment. Dermatol Clin. 1986 Jul;4(3):517-28.

Kligman LH et al. Prevention of ultraviolet damage to the dermis of hairless mice by sunscreens. J Invest Dermatol. 1982 Feb;78(2):181-9.

Kligman LH et al. Sunscreens prevent ultraviolet photocarcinogenesis. J Am Acad Dermatol. 1980 Jul;3(1):30-5.

Kligman LH et al. Sunscreens promote repair of ultraviolet radiation-induced dermal damage. J Invest Dermatol. 1983 Aug;81(2):98-102.