Joseph Weiss, M.D. [August 18 2011]
For years, we've been hearing that too much sun exposure can increase the risk of skin cancer. And yet, skin cancer remains the most common form of cancer in the United States. According to the American Academy of Dermatology, more than 3.5 million cases of skin cancer in more than 2 million people are diagnosed in the United States annually.
How does sun exposure increase cancer risk?
The sun emits ultraviolet (UV) radiation that can damage the DNA in skin cells. Exposure to excessive UV radiation can cause genetic mutations in those cells that can lead to skin cancer. The tan that some people call a “healthy glow” is actually the result of damage to the skin's DNA. The skin darkening is the body's attempt to protect itself against further radiation damage.
UV radiation from the sun includes UVA and UVB radiation, both of which can cause basal cell carcinoma and squamous cell carcinoma. These types of skin cancer form in the cells in the epidermis, the outer layer of the skin. They grow slowly and are highly treatable when caught early.
UV radiation may also cause the most dangerous form of skin cancer: malignant melanoma. This type can be fatal if not caught early because it can spread to other parts of the body.
It's not just the sun that can cause damage. Tanning beds and tanning lamps also emit UV radiation, often at higher rates than the sun. In addition to increasing the risk of basal and squamous cell carcinomas, a recent study found that people who have used tanning beds have a 75 percent higher risk of melanoma.
Besides cancer, excessive exposure to UV radiation can cause cataracts, photo-aging (wrinkles, brown spots and sagging) and weakening of the immune system.
There is good news in all of this: You can prevent sun damage and reduce your risk of skin cancer. The American Academy of Dermatology recommends:
• Protecting yourself by wearing a hat, long-sleeved shirt and sunglasses.
• Seeking shade, especially between 10 a.m. and 4 p.m., when the sun's rays are strongest.
• Using a broad-spectrum, water-resistant sunscreen with a Sun Protection Factor (SPF) of 30 or more. Broad-spectrum protects from both UVA and UVB rays. Be sure to apply enough -- one ounce, enough to fill a shot glass, is needed for proper coverage of exposed areas of the body. Sunscreen should be reapplied about every two hours and after swimming or sweating.
Joseph Weiss, M.D., is chief of Dermatology at The Hospital of Central Connecticut. For information on Hospital of Central Connecticut physicians, please contact our free Need-A-Physician referral service, 1-800-321-6244.