Melanoma skin cancer is the most aggressive of the three major categories of skin cancer, accounting for only five percent of all skin cancer cases each year, but responsible for a majority of skin cancer fatalities. An estimated 62,000 cases of melanoma are diagnosed annually, with 7,900 fatalities.

While melanoma has captured a great deal of public attention in the past 15 years, much of the discussion has been oversimplified in stating that melanoma is caused by overexposure to sunlight. In fact, the exact nature of the relationship between melanoma and ultraviolet light remains unclear, and the mechanism by which the two are related is still unknown.

Here’s why:

1. While it is believed that melanoma is somehow related to ultraviolet light exposure, this relationship is not straight-forward and the photobiology research community still does not know how it works.
2. Melanoma is more common in people who work indoors than in those who work outdoors, and those who work both indoors and outdoors get the fewest melanomas. Because this is true, the relationship between melanoma and sunlight cannot possibly be clear-cut. If it were a clear-cut relationship, outside workers would have higher incidence than inside workers. But the opposite is true.
3. Melanoma most commonly appears on parts of the body that do not receive regular exposure to sunlight. Again, because this is true, the relationship between melanoma and sunlight cannot be clear-cut. If it were, melanomas would appear most often on parts of the body that receive the most sunlight.
4. There is no actual data substantively linking indoor tanning equipment with an increased risk of melanoma. Indeed, 18 of 22 epidemiological studies ever conducted on this topic show no significant association, including the largest and most recent.
5. The reported increase in melanoma incidence in the United States may be largely explained by an increase in surveillance, an increase in the number of dermatologists per capita and the increasing number of people who see dermatologists today. There are 85 percent more dermatologists per capita today than there were 30 years ago and they are more aggressive with surveillance efforts.
6. The fact that melanoma incidence is increasing but mortality rates are declining suggests that increased surveillance is detecting more melanomas that, in previous years, were never detected. This phenomenon cannot merely be discounted.