Skin aging from ultraviolet irradiance and smoking reduces risk of melanoma: epidemiological evidence.

Long-term smoking appears to be inversely correlated with development of melanoma. Chronic ultraviolet (UV) irradiance also reduces and/or delays the development of melanoma. Thus, a common process is indicated. To examine the link between smoking and melanoma, articles reporting the relation between incidence of lung cancer and melanoma for individuals were sought. A very strong inverse correlation (r = -0.96) was found between the standardized incidence ratios for lung cancer and melanoma, passing through the value of 1 for each with a slope of -0.74. Smoking increases skin aging or elastosis in a manner similar to that of UV irradiance. Development of elastosis seems to explain why long-term smoking and chronic UV irradiance reduce the risk of melanoma. Further work is required to elucidate the mechanism whereby elastosis retards and reduces the development of melanoma.