Melanoma Risk Factors

No one knows the exact causes of melanoma. Doctors can seldom explain why one person gets melanoma and another does not.

However, 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 person’s chance of developing a disease. Still, many who do get this disease have no known risk factors.

Studies have found the following risk factors for melanoma:

• Dysplastic nevi: Dysplastic nevi are more likely than ordinary moles to become cancerous. Dysplastic 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 (more than 50) ordinary moles: Having many moles increases the risk of developing melanoma.

• Fair skin: 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.

• Personal history of melanoma or skin cancer: 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, all family members should be checked regularly by a doctor.

• 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 children’s 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.

People who are concerned about developing melanoma should talk with their doctor about the disease, the symptoms to watch for, and an appropriate schedule for checkups. The doctor’s advice will be based on the person’s personal and family history, medical history, and other risk factors.