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Sun Exposure: The Prevention of Skin Cancer
Mohamed Kashini, MD, Bernard Gordon, MD, and Ernest H. Rosenbaum, MD

Excess sun exposure can damage the skin causing premature aging and sometimes cancer. A skin protection program is vital.

Skin cancers are one of the most common second cancers, especially for those treated with radiation therapy, thus survivors should take extra care to protect their skin from sun exposure. This includes regularly using sunscreen with sun protection factor (SPF) of 15 or more, wearing hats and protective clothing for all parts of the body including hands and feet, avoiding outdoor activities from 10am to 3pm when the sun's rays are most intense, and not tanning.

Be aware of changes to your skin. Any non-healing sores, changes in skin lesions, moles or freckles merit a physician's examination.

The Dangers of Excessive Sun Exposure
Sun exposure is not only unhealthy but also causes nearly 90% of the cosmetic changes associated with aging, such as wrinkling, a leathery appearance to the skin, irregular pigmentation, and aging spots. It may also lead to photodamage, which can evolve into several forms of skin cancer, the most deadly one being malignant melanoma. It has been estimated that using sunscreen on a regular basis during the first eighteen years of life could reduce the incidence of skin cancer by up to 70%.

Tanning booths should be avoided as they present a high risk of melanomas.

Analyzing the Power of the Sun
The sun's radiation is made up of infrared, visible, and ultraviolet (UV) rays. It's the ultraviolet rays, UV-A and UV-B, which affect the skin.
- UV-B rays penetrate your skin's top layer (epidermis) and are the principle cause of sunburn and skin cancer. They are the strongest and most potentially damaging rays and are most common between 10am and 3pm.
- UV-A rays penetrate the skin even more deeply, reaching into the underlying skin layers of connective tissue. They play a major role in aging and are strong all day long, all year long.

When your skin absorbs UV rays, the exposure triggers the production of melanin, a natural sunscreen pigment, creating what is known as a tan. The skin remembers each exposure, and with each burn the skin's ability to protect itself weakens. Over years, damage to the skin's basic structure from sunlight can lead to premature aging and possibly skin cancer.

Precancerous Skin Lesions
Excess sun exposure can lead to the growth of actinic keratoses or solar keratoses - rough, scaly skin lesions that can be a precursor to cancer. People with such precancerous skin lesions are at risk for developing squamous, basal, or melanoma cancers due to excess sun exposure.

Fortunately, 90-95% of people with this type of skin cancer can be cured. There are three basic types: basal cell, squamous cell, and melanoma. Basal cell and squamous cell carcinomas are designated non-melanoma skin cancers.

Non-melanoma
Non-melanoma cancer probably accounts for more than 50% of all cancers; more than 1 million new cases were diagnosed in 2007.

Death is uncommon with these cancers. It is thought that between 1,000 and 2,000 people die each year from non-melanoma skin cancer. Most of those who die from this disease are elderly and were not treated soon enough.

Basal-cell carcinoma is the most common form and develops in sun-exposed areas of the face and body and looks like a pale, wax-like, or pearly nodule (lump) that may ulcerate.

- It is linked to ultraviolet radiation exposure usually occurring on fair-skinned people who sunburn easily but tan poorly and people who live in a warm, sunny region.
- Most basal-cell cancers are treated effectively with surgical removal; the cure rate is over 95% when treated early. It is important to use sunscreen for protection and to prevent future lesions.

Squamous-cell carcinoma occurs in the skin layer that produces protective keratin in the epidermis (top layer) and may occur anywhere on the skin - whether or not the areas have been overexposed to the sun - or on the mucous membranes. It appears as a red, scaly, raised lesion that arises on the sun-damaged skin or sites of previous burns, scars, or chronic sores.

Squamous-cell cancer is usually related to too much ultraviolet light exposure and people at risk usually are those who have fair skin and burn easily but tan poorly, and those who develop precancerous lesions such as solar keratoses.

Fortunately, when caught early, most new squamous tumors are effectively cured, but they may metastasize.

Melanoma
Although melanoma accounts for only about 4% of skin cancer cases, it causes a large majority of skin cancer deaths.

Melanoma tends to occur at a younger age than most cancers; half of all melanomas are found in people under age 57, including adolescents. The American Cancer Society estimates that more than 62,000 new melanomas will be diagnosed in the United States during 2007, of which almost 8,000 people are expected to die. Since 1973, the mortality rate for melanoma has increased by 50%. Much of this increase has been in older people, primarily white men.

Melanoma (meaning a black tumor) is a potentially deadly tumor, the most malignant type of skin cancer, and it is one of the most lethal cancers of any kind. It frequently arises in pigmented cells (melanocytes) of the epidermis (upper layer of skin) and can spread quickly to any part of the body.

Risk factors:
- A family or personal history of melanoma
- A light complexion
- A tendency to freckle
- A tendency to sunburn and a history of prior sunburns
- Any moles or birthmarks
- Unusual moles or birthmarks
- Having had high dose radiation


Symptoms:
- A change in color - lightening and/or darkening of a reddish, bluish, or grayish tinge.
- A growth or change in size, shape, or thickness.
- Irregularity of the margins of the growth.
- Itching, crusting, bleeding, erosion, or ulceration.
- Personal or family history of melanoma and/or dysplastic nevi, usually moles that look like melanoma under the microscope.
- Melanomas may develop in normal-looking skin or in dark or fleshy-colored moles.
- Melanoma is a potentially deadly form of skin cancer, but when caught early and treated early, most patients do very well. Examine your skin regularly, especially for moles, as you become a responsible partner in your own health care.
- In all three types of the disease, skin biopsies are necessary to confirm the diagnosis of cancer.

Precautions to Avoid Excess Skin Damage
- Avoid the midday sun (10:00am - 3:00pm)
- Cover up. Light, long-sleeved shirts and long pants can help shield you against the sun's ultraviolet rays. Umbrellas may be needed to deflect strong, direct sunlight or reflected light off the beach or water.
- Use sunscreens. A Sun Protection Factor (SPF) of 15 or higher offers protection.
- Avoid tanning salons.  (Increased risk for melanoma)

The Risks of Tanning Booths Versus a Good Suntan
Twenty-five states have restrictive legislation on tanning booths. Many have warning labels, and others require licensed professionals to monitor tanners, and all require parental consent for teenagers.
1. The Skin Cancer Foundation has reported that tanning booth exposure before age 35 increases a person's risk for melanoma by 75%.1
2. A 1994 Swedish study reported women 18-30 who visited a tanning booth ten times or more a year had a seven-times greater incidence of melanoma.2
3. They estimated that 28 million Americans annually visit tanning salons. David E. Fisher, M. D., who directs the Melanoma Program at the Dana Farber Cancer Center, stated, "The number one risk factor for melanoma is an inability to tan; people who tan easily or have dark pigmentation are less likely to develop the disease." Protein p53 has been shown to be linked to skin tanning; thus, there appears to be a link between the desire to have tanned skin via the sun and p53. 3
4. "Ultraviolet radiation, whether it comes from the sun or it comes from artificial devices like indoor tanning, is not safe," said Lazovich, a Ph.D. researcher and associate professor of epidemiology. 4 5. Indoor Tanning Fact Sheet American Academy of Dermatology 5

Conclusion
The best cure for skin cancer remains early detection, prompt treatment, and follow-up preventive care measures. Recognize warning signs of a disease through regular skin self-examination. Even more important, however, is to protect yourself from the sun's rays. By avoiding the peak hours of ultraviolet radiation, and by wearing sunscreen and protective clothing, you can keep skin cancer from happening to you.
References
1
(http://www.skincancer.org/skin-cancer-facts)
2
(http://www.skincancer.org)
3
Cui R, Widlund HR, Feige E, Lin JY, Wilensky DL, Igras VE, D'Orazio J, Fung CY, Schanbacher CF, Granter SR, Fisher DE., Central role of p53 in the suntan response and pathologic hyperpigmentation. Cell 2007 Mar 9;128(5):853-64.
4
Lazovich D, Vogel RI, Berwick M, Weinstock MA, Anderson KE, Warshaw EM., Indoor Tanning and Risk of Melanoma: A Case-Control Study in a Highly Exposed Population. Cancer Epidemiol Biomarkers Prev. 2010 May 26.
5
American Academy of Dermatology, Indoor Tanning Fact Sheet (http://www.aad.org/media/background/factsheets/fact_indoortanning.html)



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