Incidence of malignant melanoma of the skin in England and Wales and its relationship to sunshine.

In most of England and Wales the incidence of malignant melanoma of the skin has risen rapidly in recent years, especially in women. Mean incidences in the 14 English health regions and Wales correlated negatively with latitude and positively with hours of sunshine, suggesting that exposure to sunshine was an important causal factor. Male and female incidences within a region tended to show similar yearly fluctuations, implying a common factor affecting the incidence in both men and women with a short latent period of action. This factor may be exposure to sunshine, which may cause melanoma after an induction period of about two years; for women the incidence of melanoma in the regions of England and Wales correlated positively with hours of sunshine two years earlier.