Booklet: What You Need to Know about Melanoma

Causes, Risk Factors, and Prevention

Researchers at hospitals and medical centers all across the country are studying melanoma. They are trying to learn what causes the disease and how to prevent it.

At this time, the causes of melanoma are not fully understood. It is clear, however, that this disease is not contagious; no one can "catch" cancer from another person.

Researchers study patterns of cancer in the population to look for factors that are more common in people who develop melanoma than in people who don't develop this disease. It is important to know that most people with these risk factors do not get cancer, and people who do develop melanoma may have none of these factors.

 

Risk factors for melanoma: Family history of melanoma Dysplastic nevi Previous melanoma Immunosuppressive therapy Many ordinary moles (more than 50) Severe, blistering sunburns Many freckles Fair skin, light eyes

Scientists have observed that certain factors increase a person's chance of developing melanoma. For example, having two or more close relatives who have had this disease is a risk factor because melanoma sometimes runs in families. In fact, about 10 percent of all patients with melanoma have family members who also have had this disease. When melanoma runs in a family, the family members should be checked regularly by a doctor.

Certain types of mole patterns are associated with an increased risk of developing melanoma, such as having dysplastic nevi (atypical moles). As described in the Signs and Symptoms of Melanoma section, dysplastic nevi are more likely than ordinary moles to become cancerous. Many people have only a few of these abnormal moles; the risk of melanoma is greater for people with a large number of dysplastic nevi. The risk is especially high for people who have a family history of both dysplastic nevi and melanoma. Having an unusually high number of moles (more than 50) is another risk factor for melanoma. Also, people whose immune system is weakened by certain cancers, by drugs given following organ transplants, or by AIDS are at increased risk of developing melanoma.

The number of people who develop melanoma is increasing. Researchers believe that the number of melanomas may be increasing because people are spending more time in the sun. They know that ultraviolet (UV) radiation from the sun causes premature aging of the skin and skin damage that can lead to melanoma. (Two types of ultraviolet radiation--UVA and UVB--are explained in the Glossary section.) Artificial sources of UV radiation, such as sunlamps and tanning booths, also can cause skin damage and probably an increased risk of melanoma.

People who have had one or more severe, blistering sunburns as a child or teenager are at increased risk for melanoma. Because of this, doctors advise protecting children's skin from the sun, which they hope will help prevent, or at least reduce the risk of melanoma later in life. Sunburns in adulthood are also a risk factor for melanoma.

Melanoma occurs more frequently in people who have fair skin that burns or freckles easily (these people also usually have red or blond hair and blue eyes) than in people with dark skin. White people get melanoma far more often than do black people, probably because light skin is more easily damaged by the sun. In addition, this disease is more common in people who live in areas that get large amounts of UV radiation from the sun. In the United States, for example, melanoma is more common in Texas than it is in Minnesota, where the sun is not as strong.

To help prevent and reduce the risk of melanoma, people should avoid exposure to the midday sun (from 10 a.m. to 2 p.m. standard time, or from 11 a.m. to 3 p.m. daylight saving time) whenever possible. Another simple rule is to protect yourself from the sun when your shadow is shorter than you are. Wearing a hat and long sleeves offers protection. Also, lotions or creams that contain sunscreens help prevent sunburn. Many doctors believe sunscreens may help prevent melanoma, especially those that block or absorb both types of ultraviolet radiation. Sunscreens are rated in strength according to a sun protection factor (SPF). Those rated 15 or higher give the best protection. Sunglasses that have UV-absorbing lenses should also be worn. The label should specify that the lenses block at least 99 percent of UVA and UVB radiation.

People who think they may be at risk for developing melanoma should discuss this concern with their doctor. The doctor may suggest ways to reduce the risk and can plan an appropriate schedule for checkups.

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