Melanoma is a malignant tumor of melanocytes. Melanocytes predominantly occur in the skin but can be found elsewhere, especially the eye. The vast majority of melanomas originate in the skin. While it represents one of the rarer forms of skin cancer, melanoma underlies the majority of skin cancer-related deaths. Despite many years of intensive laboratory and clinical research, the sole effective cure is surgical resection of the primary tumor before it achieves a thickness of greater than 1 mm. Melanoma of the skin accounts for 160,000 new cases worldwide each year, and is more frequent in white men. It is particularly common in white populations living in sunny climates. According to the WHO Report about 48,000 deaths worldwide due to malignant melanoma are registered annually. Generally, an individual's risk for developing melanoma depends on two groups of factors: intrinsic and environmental. "Intrinsic" factors are generally an individual's family history and inherited genotype, while the most relevant environmental factor is sun exposure.