Sunscreen and Skin Cancer

Apply sunscreen generously. Skimpy application can reduce the sun protection factor (SPF) by up to 50 percent.

Thanks to our love affair with the sun, skin cancer is on the rise. With this in mind, taking precautions becomes paramount. So what about sunscreen? Can sunscreen protect you from skin cancer?

This is an important question. With more than 2 million new cases reported in the U.S. annually, skin cancer is the most common form of cancer. And these numbers don't even include melanoma, the most serious form of skin cancer. Although most cases are highly curable, especially when detected early, treating skin cancer can be costly and difficult.

There are three main forms of skin cancer: basal cell, squamous cell, and melanoma. Like other cancers, skin cancer is influenced by genetics, so those with a family history of skin cancer are at higher risk. The most obvious sign of this genetic relationship is skin type. Fair-skinned people are at greater risk than darker-skinned people. However, the major culprit in the rise of all forms of skin cancer, regardless of genetics, melanoma included, is sun exposure.

Years ago, a golden tan was considered unfashionable and people went to great lengths to protect themselves from the sun. Many of us have seen old photographs showing women at the beach in floor-length dresses with long sleeves. Gradually, however, modest outfits gave way to bikinis and generations of sun worshipers were born.

How the sun damages skin

We used to think that it took decades for sun damage to accumulate, and that skin cancer developed no sooner than middle age. Now younger and younger people are being diagnosed. The reason for this change is not clear. It could relate to more sun exposure because of more leisure time, or even increased use of tanning parlors. Light-skinned races, such as Caucasians, are the most vulnerable. But African-Americans and those with darker skin are not immune, although they develop skin cancer far less frequently.

What role does the sun play? The sun is a source of radiation, which it emits in two types of rays: UVA (ultraviolet A) and UVB (ultraviolet B). Although the UVA rays produce less skin redness than the shorter UVB rays, these longer rays are more damaging to skin cells. Ultraviolet rays not only cause skin cancer, but also cause other effects from the sun, such as wrinkles and age spots. These skin changes were once attributed solely to aging, but they are now recognized as the results of long-term sun exposure. Those who live in sunny climates year-round have higher skin cancer rates. But don't be fooled; radiation from the sun can also occur on cloudy days, so sun protection is important no matter where you live and whether or not it's sunny out.

How sunscreens protect you

Sunscreens are protective substances. They extend the length of time you can be outside before your skin begins to redden, but they don't give you total protection. Using sunscreen doesn't give you liberty to stay out in the sun indefinitely, since damage to the skin cells is still occurring.

How to pick the right sunscreen

You can judge the protectiveness of a sunscreen according to its SPF, which stands for sun protection factor. For instance, if your skin usually turns pink after 10 minutes, a sunscreen with an SPF of 15 extends this to 2.5 hours (10 minutes multiplied by the "15" protection factor = 150 minutes). Here are some general recommendations for sunscreen from the American Academy of Dermatology:

• Everyone should use a broad-spectrum sunscreen having an SPF of at least 30.

• Look for broad spectrum sunscreens that block both UVA and UVB radiation.

• Check for ingredients that screen UVA: oxybenzone, sulisobenzone, titanium dioxide, zinc oxide, and butyl methoxydibenzoylmethane (also called avobenzone and known by the trade name Parsol 1789).

• Know that sunscreen labeled "waterproof" or "very water resistant" offers 80 minutes of protection and sunscreen labeled "water resistant" offers about 40 minutes of protection.

But if SPF 30 is good, isn't a higher number better? Perhaps, but it depends on your individual characteristics. For instance, if you're particularly fair skinned, live at a high altitude where the sun's rays are stronger, or spend a lot of time outdoors, you may want to choose a sunscreen with a higher SPF number.

How to be in the sun safely

Follow these tips for safe sunning:

• Use sunscreen year-round, even when it's cloudy out.

• Whether you prefer your sunscreen in the form of a cream, oil, lotion, or gel is up to you. However, some oils have very low SPF levels. Remember, too, that you need to reapply all sunscreens periodically, and you need to reapply gels more often. New continuous spray sunscreen may make it easier to apply sunscreen to hard-to-reach areas.

• Apply sunscreen generously. When applied too skimpily, the SPF may be half that advertised on the product.

• Choose sunscreen labeled "waterproof" or "very water resistant." Also, chose a sunscreen labeled "broad spectrum," meaning it screens out both UVA and UVB rays. However, bear in mind that there is no standardized test for broad spectrum products.

• Limit your sun exposure between 10 a.m. and 4 p.m., when ultraviolet rays are the strongest.

• Use a sunscreen if you're going to be outdoors for more than 20 minutes. Apply the sunscreen 15 to 30 minutes before going outdoors. If you're going swimming, or if you're doing an activity that causes you to sweat, reapply the sunscreen afterward, and again every two hours.

• Wear a hat with a wide brim and tightly woven clothing that covers most of your skin, as well as sunglasses.

• Protect your children as well. Teach older children safe sun habits, including playing in the shade, wearing protective clothing, and applying sunscreen. Keep infants under 6 months of age out of direct sun, keep their skin covered, and use an umbrella over their stroller. Use sunscreen on them beginning at 6 months of age.

Tanning beds and sun lamps

Many people believe that the UV rays of tanning beds are harmless because sunlamps in tanning beds emit primarily UVA and little, if any, UVB, the rays once thought to be the most hazardous. Plus, they are regulated by the FDA.

But no matter what the regulations say, these lamps do emit UVA rays, and UVA rays can cause serious skin damage, too, which can lead to skin cancer. According to some scientists, UVA may be linked to the most serious form of skin cancer, melanoma. Because of the dangers, health experts advise people to avoid sunlamps for tanning.