The Cancer Season
As summer beckons, we should take a moment to focus on the sun's dark side. The source of all life on Earth, the sun is also a fountain of environmental carcinogens. Specifically, we now know that the sun's ultraviolet radiation is the primary cause of most skin cancers.
Skin cancer, long thought to be a disease of little public health significance, has now become epidemic. An estimated 90,000 new cases of malignant melanoma and well over one million cases of non-melanoma skin cancer will occur in the United States this year. Melanoma will cause 8,000 deaths, and non-melanoma skin cancer will kill another 2,000. Melanoma is now the most common cancer in women aged 24 to 35. Once a disease of men in their fifties and sixties, it is not unusual for women in their twenties to develop basal cell cancer or squamous cell cancer.
While the incidence of skin cancer has risen dramatically, so has our understanding of its causes. For over fifty years, ultraviolet radiation from the sun has been the number one suspected cause of skin cancer. Epidemiologic data from Australia, animal studies with artificial sources of ultraviolet light, and the development of skin cancer in individuals with a genetic inability to correct the DNA damage caused by ultraviolet radiation provided circumstantial evidence of the connection. Recent work has made the causal link between the sun and skin cancer at the molecular and cellular level.