In the United States, malignant melanoma is the fifth most prevalent cancer among men and the sixth most common in women, and the incidence has been increasing every year over the last several decades (1). The median age at diagnosis for melanoma is 59 years, and approximately 21% of the patients are under 45 years of age at the time of diagnosis (2). In women in the 25 to 29-year age group, melanoma is the most common cancer. In women between 30 and 34 years of age, it is the second most common type of malignancy, breast cancer being the most common (3). Between 2002 and 2006, the age-adjusted incidence for cutaneous malignant melanoma was 19.6 per 100,000 males and females per year in the United States (2). The high rate of malignant melanoma in the United States is surpassed only in Australia, New Zealand, Norway, and Israel. Although the incidence of melanoma in the United States rose dramatically from the 1970s through the 2000s, this trend appears to be slowing for those born after 1945 (2,4). The cause for the slowing trend is multifaceted, including reduced exposure to ultraviolet rays, widespread use of sunscreen, and improvements in community-based education and screening.
Malignant melanoma is mostly curable if identified at an early stage. Therefore understanding the host and environmental factors that predispose individuals to an increased risk is of paramount importance. Those individuals at increased risk of developing melanoma benefit from regular screening examinations and education regarding the warning signs of melanoma.
Exposure to ultraviolet light is the most significant cause of the development of skin melanoma (5,6), as suggested by the fact that the increase in incidence of cutaneous melanoma is associated with the increasing distance from the poles (7-10) and that freckles and nevi, the risk factors for the development of melanoma, are induced by exposure to sunlight (11-13). In addition, severe sunburns during adolescence years and the use of tanning beds have been linked to an increased risk of cutaneous melanoma (5,14).
The color of the skin is related to the risk of developing cutaneous melanoma. The age-adjusted incidence rates of malignant melanoma are lower in ethnic groups with darker skin colors. For instance, the incidence rates among white, Hispanic, and black populations are 28.9, 4.6, and 1.1 per 100,000 men, respectively, and 18.7, 4.7, and 1.0 per 100,000 women, respectively (2). In addition, people whose skin tends to burn easily with sun exposure have a higher risk of melanoma (15-17). Likewise, lighter hair color or red hair and blue eye color are associated with a greater risk of developing melanoma (relative risks of 1.5-2.4 fold) (18).
Although commonly acquired nevi typically appear after the first year of life and are benign in and of themselves, several studies ...