A risk factor is anything that increases a person's chance of getting a disease such as cancer. Although these factors increase your risk, they do not necessarily cause the disease to develop. Many people with risk factors never develop cancer, while others with this disease have no known risk factors.

Causes

Ultraviolet (UV) radiation from the sun is the main cause of skin cancer. Most ultraviolet radiation comes from sunlight, but some may come from artificial sources, such as tanning booths or sunlamps. Ultraviolet rays can damage DNA, the genetic material found in our cells. When DNA is damaged, it is less able to control how and when cells grow and divide. This may result in the formation of cancer.

Sometimes it only takes a few years for skin cancer to develop. However, many times skin cancer results from UV exposures that happened many years earlier. Children and young adults often receive intense ultraviolet sun exposure that may not lead to skin cancer for many years or even decades.

Abnormal moles can also be a cause of melanoma. Although most moles never turn into a melanoma, some do.

Factors

Geographic Location
People who live in areas that get high levels of UV radiation from the sun are more likely to get skin cancer.

Lifetime exposure to UV radiation
Although most skin cancers don't appear until after age 50, the damaging effects of the sun's UV rays begin early in life. Therefore, protection against UV rays should begin during childhood.

Exposure to midday sun
The sun's rays are most harmful during the hours of 10 a.m. to 2 p.m. standard time or from 11 a.m. to 3 p.m. daylight savings time. It is especially important to wear protective clothing and sunscreen lotion during these hours.

Family or personal history of melanoma
According to the National Cancer Institute, having two or more close relatives with melanoma can increase a person's chances of getting the disease. Also, if you have had melanoma in the past, your chances of getting it again increase.

Abnormal moles
Also called dysplastic nevi, abnormal moles are more likely to become cancerous than ordinary moles. The more abnormal moles a person has, the greater his or her chances of getting melanoma.

Many normal moles
If you have an unusually high number of moles (more than 50), you are at increased risk of developing melanoma.

Immunosuppressive therapy
People whose immune system is weakened by cancers, drugs given following organ transplants, or AIDS are at increased risk of developing melanoma.

Severe, blistering sunburns
If you have had one or more severe, blistering sunburn during your lifetime, you are at increased risk for melanoma.

Many freckles, fair skin, light eyes
Melanoma occurs more frequently in people with fair skin that burns or freckles easily. Often, these people also have red or blond hair and blue eyes.

Age
About half of all melanomas occur in people over the age of 50. However, young people (ages 20 to 30) can also be diagnosed with melanoma. In fact, melanoma is one of the most common cancers in people less than 30 years of age.
 

Precautions

Minimize sun exposure, especially during the peak sun hours of 10 a.m. and 2 p.m. (standard time) or 11 a.m. to 3 p.m. (daylight savings time) when the sun's rays are the most intense.

Apply a sunscreen liberally and frequently, and reapply every two hours when working, playing, or exercising outdoors, even on cloudy days. Sunscreens with a sun protection factor (SPF) of at least 15 are recommended.

Wear appropriate clothing during prolonged periods in the sun, including a hat, long-sleeved shirt, and pants.

Beware of reflective surfaces. Sand, snow, concrete and water can reflect up to 85 percent of the sun's damaging rays.

Avoid tanning salons and sunlamps since the ultraviolet rays emitted by these artificial sources are similar to those in sunlight and can cause sunburn, premature aging and increased risk of skin cancer.

Protect children by keeping them out of the sun or minimizing sun exposure and applying sunscreen beginning at six months of age.

Teach children and teenagers about sun protection, since sun exposure damage accumulates over the course of a lifetime. One severe childhood or adolescent sunburn doubles the risk of developing skin cancer.

Examine your and your children's skin regularly for any changes in moles, freckles or skin discolorations.