05 March 2007

Skin cancer - prevention is key

If you spent a lot of time when you were young lying in the sun, you probably never thought how those sunny days would catch up with you.

If you spent a lot of time when you were young lying in the sun, you probably never thought how those sunny days would catch up with you.

Eighty percent of sun damage to your skin occurs before you turn 18, but it takes years before the results of that damage, from the ultraviolet (UV) radiation, appear in the form of skin cancer or photoageing, which is premature aging of the skin.

But help may be on the way. Researchers are looking into how a wide variety of compounds, including skin creams, food, vitamins and drugs, may act as agents to inhibit or reverse skin cancer and photoageing.

Vitamin A, grape seed and soybean extracts, green tea, aspirin, and non-steroidal, anti-inflammatory drugs are among the compounds being investigated, says Dr James M. Spencer, an associate professor in the department of dermatology at Mount Sinai School of Medicine in New York City.

An article he wrote outlining the research was published in a recent issue of the journal Cosmetic Dermatology.

"Other than that very first step, the absorption of the light, there are many other steps where we can intervene," he says.

For years, researchers have been looking at chemoprevention for internal cancers like breast and colon cancer, but it's only recently that scientists have started to look at it in relation to skin cancer, Spencer says.

While still in the early stages, this line of research could produce important results within the next few years, he says.

"The only one that's really firmly established to work is vitamin A and (its derivatives) called the retinoids," Spencer says.

Vitamin A should be applied topically in the form of a cream, not taken in the form of vitamin tablets. Too high a dose of Vitamin A tablets can damage your liver and is especially dangerous to pregnant women.

Among the other compounds, the most promising include polyphenolic antioxidants, found in green tea and grape seed extract.

In other skin cancer research news, a new study finds that men who are middle-age and older are not detecting melanoma, the deadliest form of skin cancer, in its early stages when it is most curable. This group is least likely to perform monthly skin self-examinations or visit a dermatologist regularly.

According to this study, more than 44 percent of people diagnosed with melanoma were men over the age of 50, even though they made up only 25 percent of those screened. Melanoma was three times as common among middle-age and older men than among all others screened.

And a third study shows that regular reapplication of sunscreen is the most important factor in determining its effectiveness. The study followed skiers in Colorado for one week in January. Skiers who reapplied sunscreen every 2.5 hours or more were five times more likely to sunburn compared to the skiers who reapplied sunscreen every two hours or less. And it didn't matter whether the sunscreen was SPF 15 or 30.

"We thought SPF would make a difference. It turns out it didn't. What made the biggest difference was how frequently they applied the sunscreen,'' says study lead author Dr Darrell Rigel, clinical professor, New York University Medical Centre.

Rigel says it's important to reapply your sunscreen whether you're in the mountains, at the beach, or in your backyard.

"The reality is that, no matter where you are, the sunscreen begins to not work as effectively after about two hours," Rigel says.

Both studies were presented at a recent AAD press conference.

What to do

Here are AAD recommendations on effective sunscreen use:

  • Wear a broad-spectrum sunscreen with a SPF of at least 15.
  • Use sunscreens every day if you're going to be in the sun for more than 20 minutes.
  • Apply sunscreens to dry skin 15 to 30 minutes before going outside.
  • When applying sunscreen, pay close attention to your face, ears, hands and arms. Generously coat skin not covered by clothing.
  • One ounce of sunscreen, enough to fill a shot glass, is the amount needed to cover the exposed areas of your body.
  • Reapply sunscreen every two hours or immediately after swimming or strenuous activity.
  • Other ideas for sun protection: Avoid deliberate tanning with indoor or outdoor light, wear protective clothing, limit sun exposure during peak hours.
  • The AAD offers the "ABCD rule" to look for warning signs of melanoma when looking at a mole during a skin self-examination:

  • Asymmetry - One-half of the mole doesn't match the other half.
  • Border irregularity - The edges of the mole are ragged, notched or blurred.
  • Colour - The pigment of a changing mole is not uniform and may include shades of tan, brown, black and even red, white or blue.
  • Diameter - A mole larger than six millimetres, about the size of a pencil eraser, should be of concern.


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