SKINIPEDIA - Skin Cancers: Melanoma & Ultraviolet Radiation

Melanomas

Melanomas can occur anywhere on the body, but are more likely to develop in certain locations. The trunk (chest and back) is the most common site in men. In women, the legs are the most common site. The neck and face are other common sites.

Melanoma occurs much less often than basal cell and squamous cell skin cancers, but it can be far more serious. Like basal cell and squamous cell cancers, melanoma is almost always curable in its early stages. But if left alone, melanoma is much more likely than basal or squamous cell cancer to spread to other parts of the body, where it can be very hard to treat.

What is Ultraviolet (UV) Radiation?

Ultraviolet (UV) radiation is thought to be the major risk factor for most skin cancers. Sunlight is the main source of UV radiation, which can damage the genes in your skin cells. Tanning lamps and booths are also sources of UV radiation. People with excessive exposure to UV radiation from these sources are at greater risk for skin cancer.

Ultraviolet radiation has 3 wave length ranges:

• UVA rays cause cells to age and can cause some damage to cells' DNA. They are linked to long-term skin damage such as wrinkles, but are also thought to play a role in some skin cancers.
• UVB rays can cause direct damage to the DNA, and are the rays that primarily cause sunburns. They are also thought to cause most skin cancers.
• UVC rays don't penetrate our atmosphere and therefore are not present in sunlight. They are not normally a cause of skin cancer.

UVA and UVB rays make up only a very small portion of the sun's wavelengths, but they are the main cause of the damaging effects of the sun on the skin. UV radiation damages the DNA of skin cells. Skin cancers begin when this damage affects the DNA of genes that control skin cell growth. Both UVA and UVB rays damage skin and cause skin cancer. UVB rays are a more potent cause of at least some skin cancers, but based on current knowledge, there are no safe UV rays.

The amount of UV exposure depends on the intensity of the radiation, the length of time the skin was exposed, and whether the skin was protected with clothing or sunscreen.

Skin cancers are one result of getting too much sun, but there are other effects as well. The short-term results of unprotected exposure to UV rays are sunburn and tanning, which are signs of skin damage. Long-term exposure can cause prematurely aged skin, wrinkles, loss of skin elasticity, dark patches (lentigos, sometimes called age spots or liver spots), and pre-cancerous skin changes (such as dry, scaly, rough patches called actinic keratoses).

The sun's UV rays also increase a person's risk of cataracts and certain other eye problems and can suppress the skin's immune system. Although dark-skinned people are generally less likely to get skin cancer than light-skinned people, they can still get cataracts and suppression of the skin's immune system.

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