Prevention:

The best way to lower your risk of skin cancer is to protect your skin from the sun and UV light. That means avoiding excess sun exposure, especially in midday when the sun is strongest.

Wear sunscreen. The use of sunscreens is complex, and everyone should understand how and when to use them. Follow instructions closely and reapply as directed after swimming or sweating. The bottom line is not that people should avoid sunscreens or sunblocks, but that they should always use them in combination with other sun-protective measures.

Many parents are now taking effective steps to protect their children, although experts worry that they are relying too much on sunscreen and less on other protective measures.

General Guidelines for Avoiding the Sun and UV Radiation

The best way to prevent skin damage in any case is to avoid excessive sun exposure. The following are some specific guidelines:

• Use sunscreens that block out both UVA and UVB radiation. Do not rely on sunscreen alone for sun protection. Also wear protective clothing and sunglasses.
• Avoid sun exposure, particularly during the hours of 10 a.m. to 4 p.m., when UV rays are the strongest.
• Use precautions, even on cloudy days. Clouds and haze do not protect you from the sun, and in some cases may intensify UVB rays.
• Avoid reflective surfaces such as water, sand, concrete, and white-painted areas.
• UV intensity depends on the angle of the sun, not heat or brightness. The dangers are greater the closer to the start of summer.
• Skin burns faster at higher altitudes. One study suggested that an average complexioned person burns in 6 minutes at 11,000 feet at noon compared to 25 minutes at sea level.
• Avoid sun lamps, tanning beds, and tanning salons. The machines use mostly high-output UVA rays.

Sun-Protective Clothing

Wear protective clothing, sunglasses, and a hat to shield your face from the sun's rays. Special clothing can block out UV rays. This clothing is rated using sun protection factor (SPF) or a system called the ultraviolet protection factor (UPF) index, with 50 UPF being the highest. (According to one study, this is a very reliable indicator of protection.) The clothing is expensive, however.

• Everyone, including children, should wear hats with wide brims. (Even wearing a hat, however, may not fully protect against skin cancers on the head and neck.)
• Look for loose-fitting, unbleached, tightly woven fabrics. The tighter the weave, the more protective the garment.
• Washing clothes over and over improves UPF by drawing fabrics together during shrinkage. An easy way to assess protection is simply to hold the garment up to a window or lamp and see how much light comes through. The less light the better.
• Everyone over age 1 should wear sunglasses that block all UVA and UVB rays when in the sun.

Sunscreen Guidelines

When choosing a sunscreen, look at the ingredients. Preparations that help block UV radiation are sometimes classified as sunscreens or sunblocks, according to the substances they contain. In general, sunscreens contain organic formulas and sunblocks inorganic formulas. However, the term sunblock is used less and less as sunscreens increasingly contain both kinds of ingredients:

• Organic formulas contain UV-filtering chemicals such as octocrylene, octyl salicylate, homosalate, and octyl methoxycinnamate (block UVB), avobenzone-Parsol 1789 (blocks UVA), cinoxate, ethylhexyl p-methoxycinnamate (blocks UVB and small amounts of UVA), oxybenzone, and benzophenone-3 (blocks UVA/UVB). Look for a wide-spectrum sunscreen that contains combinations of these ingredients and filters both UVA and UVB light.
• Inorganic formulas contain the UV-blocking pigments zinc oxide or titanium dioxide. Zinc and titanium oxides lie on top of the skin and are not absorbed. They prevent nearly all UVA and UVB rays from reaching the skin. Older sunblocks were white, pasty, and unattractive, but current products use so-called microfine oxides, either zinc (Z-Cote) or titanium. They are transparent and nearly as protective as the older types.

Inexpensive products with the same ingredients work as well as expensive ones. The FDA continues to work toward improved use and label guidelines for manufacturers.

The safety and efficacy of combination sunscreen and insect repellant remains unclear. While suncreen should be re-applied frequently, insect repellant applied too often could pose toxicity.

Organic formulas and inorganic microfine oxides do not protect against visible light, which is a problem for people who have light-sensitive skin conditions, including actinic prurigo, porphyria, and chronic actinic dermatitis.

Calculating SPF. SPF is a ratio based on the amount of UVB radiation needed to turn sunscreen- or sunblock-treated skin red compared to non-treated skin. For instance, people who sunburn in 5 minutes and who want to stay in the sun for 150 minutes might use an SPF 30 sunscreen. The formula would be: 30 (the SPF number) times 5 (minutes to burn) = 150 minutes in the sun.

Protection offered by sunscreens may be classified as follows:

• Minimal: SPF 2 to 11
• Moderate: SPF 12 through 29
• High: SPF 30+

Although some sunscreens claim their SPF is higher than 30, the added protection at such higher levels is insignificant.

SPF Levels by Age Group. Although sunscreens are safe in most toddlers and children, they should not be the first and only lines of defense. All young children should be well-covered with clothing, sunglasses, and hats. Children should be kept out of the sun during peak sunlight periods. Do not use sunscreens on babies younger than 6 months without consulting a doctor.

Older children and adults (even those with darker skin) benefit from using SPFs of 15 and over. Some experts recommend that most people should use SPF 30 or higher on the face and 15 or higher on the body. Adults who burn easily instead of tanning and anyone with risk factors for skin cancer should use SPF 50+.

Timing and Amount of Application. Apply sunscreen or sunblock liberally as follows:

• Adults should wear sunscreen every day, even if going outdoors for only a short time.
• Apply a large amount to all exposed areas, including ears and feet. To get the level of protection indicated by the sunscreen's SPF, experts recommend half a teaspoon each for the head, neck, and each arm and a teaspoon each for the chest area, back, and each leg.
• Apply sunscreen or sunblock 30 minutes before venturing outdoors for best results. This allows time for the sunscreen to be absorbed. Then reapply every 15 - 30 minutes while out in the sunlight.
• Also reapply each time after exercise or swimming, or at least every two hours. Choose a waterproof or water-resistant formula, even if your activities don't include swimming. Waterproof formulas last for about 40 minutes in the water, whereas water-resistant formulas last half as long.

Possible Hazards of Sunscreens, Sun Avoidance, or Both. When used generously and appropriately, sunscreen products and sun avoidance help reduce the severity of many aging skin disorders, including squamous cell cancers. There are certain concerns, however. Sunscreens do not appear to protect against melanoma and some basal cell cancers. In fact, some studies have reported a higher association with sunscreen use and these skin malignancies, though not all studies report such negative results.

The reasons for this possible increased risk are unclear, though some theories include:

• Until recently, many sunscreens only or predominantly blocked UVB rays and not UVA, the more deeply penetrating rays now known to be especially dangerous. Studies then may not have reflected the effects of the broad-spectrum sunscreens now available, which block both UVA and UVB.
• People who apply sunscreens may stay out too long during peak sunlight hours. Even if a person doesn't sunburn, UVA rays can still penetrate the skin and do harm.
• People may not put on enough sunscreen.

Chemoprevention

Chemoprevention is the use of a substance to prevent or reduce your risk of cancer. Certain drugs have been used to help block the development of skin cancers, including melanoma. These include:

• A medicine called imiquimod is approved to prevent skin cancer in certain people. This medicine prompts the immune system to fight off foreign substances, including cancer cells.

Chemopreventive drugs under investigation that show promise for skin cancer include:

• Nonsteroidal anti-inflammatory drugs.
• Retinoids have been shown to prevent nonmelanoma skin cancer in patients with basal cell nevus syndrome, xeroderma pigmentosum, and transplanted organs. Oral retinoids include isotretinoin and acitretin. These medications may also prevent the development of squamous cell carcinoma in patients who are taking them to treat psoriasis.

Antioxidants, Vitamins, and Herbal Products

Antioxidants are chemicals or drugs that help prevent cell damage from unstable molecules called free radicals. Antioxidants promoted to protect the skin include vitamins C and E, and coenzyme Q10 (CoQ10).

There are wide claims about the benefits of antioxidants for wrinkles when used in skin creams. To date, only skin products containing vitamins E and C, and selenium have been shown to help reduce sun damage to the skin. However, most available brands contain very low concentrations of these antioxidants. In addition, the antioxidants are not well absorbed by the skin, so the effect may be short-term. Plus there is no evidence that they prevent skin cancer.

Warning: A wide range of herbal products may contribute to skin problems. Some Chinese herbal creams have been found to contain corticosteroids. Mercury or arsenic contaminants have been found in some Ayurvedic therapies. In addition, several oral herbal remedies used for medical or emotional conditions may produce irritation in reaction to sunlight (photosensitivity). They include, but are not limited to, St. John's wort, kava, and yohimbe.