II. Causes:
Sunlight
is thought to be the most important cause of malignant
melanoma. There has been an
alarming increase in the number of new cases of melanoma each year.
Malignant melanoma is
increasing in quantity more than any other
cancer. This may be a result of the depletion of the ozone layer. The ozone is
that part of the atmosphere that blocks ultraviolet light. Ultraviolet light (a
fraction of sunlight which penetrates clouds) is thought to be a major cause of
melanoma. It is estimated that one person in 100 in the United States will
develop malignant melanoma during their lifetime. Although the number of new cases (per
1,000 people) is higher in all three counties in Delaware compared to the
national average, the highest rate is in Sussex county. This is thought to be
related to the increased occupational and recreational sun exposure in Sussex
county residents. In Delaware these statistics are higher for both white males
and females. Melanoma occurs most frequently between the ages of 20 and 60, but
can occur at any age. It is now the most common type of cancer in women from
ages 25-29.
Malignant melanoma is seen mainly not in outdoor workers, but in indoor professionals. This is considered to be due to the fact that indoor workers get bursts of sunlight on weekends and holidays. It is thought that these short bursts of sunlight are responsible for the development of this cancer. People who are light in skin tone, fair hair, and who have a family member who has had a malignant melanoma need to be particularly careful and should have a complete skin exam each year. A history of melanoma in the family leads to a greater chance of developing a melanoma. The person at greatest risk is the light-skinned, indoor worker who gets bursts of sunlight during weekends or holidays.