What Causes Melanoma
Sunlight is the main environmental agent that causes melanoma. However, the exact wavelengths of sunlight that cause melanoma are unknown. Research has shown that people with certain risk factors are more likely than others to develop melanoma. A risk factor is anything that increases a personís chance of developing a disease. Still, many get this disease with no known risk factors.
The following are established risk factors for melanoma:
Dysplastic moles (nevi) are common, and many people have a few of these abnormal moles. The risk of melanoma is greatest for people who have a large number of dysplastic nevi. The risk is especially high for people with a family history of both dysplastic nevi and melanoma.
Many ordinary moles (more than 50)
Having many moles increases the risk of developing 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. Caucasians get melanoma far more often than do black people, probably because light skin is more easily damaged by the sun.
Personal history of melanoma or other skin cancers
People who have been treated for melanoma have a high risk of a second melanoma. Some people develop more than two melanomas. People who had one or more of the common skin cancers (basal cell carcinoma or squamous cell carcinoma) are at increased risk of melanoma.
Family history of melanoma
Melanoma sometimes runs in families. Having two or more close relatives who have had this disease is a risk factor. About 10 percent of all patients with melanoma have a family member with this disease. When melanoma runs in a family, a doctor should check all family members regularly.
Weakened immune system
People whose immune system is weakened by certain cancers, by drugs given following organ transplantation, or by HIV are at increased risk of developing melanoma.
Severe, blistering sunburns
People who have had at least one severe, blistering sunburn as a child or teenager are at increased risk of melanoma. Because of this, doctors advise that parents protect childrenís skin from the sun. Such protection may reduce the risk of melanoma later in life. Sunburns in adulthood are also a risk factor for melanoma.
Ultraviolet (UV) radiation
Experts believe that much of the worldwide increase in melanoma is related to an increase in the amount of time people spend in the sun. This disease is also 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 in Minnesota, where the sun is not as strong. UV radiation from the sun causes premature aging of the skin and skin damage that can lead to melanoma. Artificial sources of UV radiation, such as sunlamps and tanning booths, also can cause skin damage and increase the risk of melanoma. Doctors encourage people to limit their exposure to natural UV radiation and to avoid artificial sources.