Causes of Melanoma
Dysplastic nevi are more likely than ordinary moles to become cancerous. Dysplastic nevi are common, and 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.
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 darker skin. Caucasians get melanoma far more often than African Americans because the sun easily damages light skin.
Personal History of Skin Cancer
People who have been treated for melanoma have a high risk of a second melanoma. People who have had one or more of the common skin cancers (basal cell or squamous cell carcinoma) are at increased risk 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 are at an increased risk of developing melanoma. A weakened immune system can be caused by:
- Certain cancers
- Drugs given following organ transplantation
- Human immunodeficiency virus (HIV).
People who have had at least one severe, blistering sunburn as a child or teenager are at increased risk of melanoma. Doctors advise parents to protect their 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.