Erythema, skin cancer risk, and sunscreens

Ultraviolet-induced erythema is now recognized as an important clinical marker for skin cancer risk. People with a history of repeated erythematous exposures to sunlight are more likely to develop both melanoma and nonmelanoma skin cancers. Is erythema the most important thing we need to be concerned about in terms of protecting the public from the harmful effects of sunlight? What do we know about UV-induced erythema, and why is it a powerful influence on skin cancer risk?