Sunscreens prevent sunburn. They do so by stopping the ultraviolet (UV) burning rays of the sun from reaching the skin. Skin cancer is the most common type of cancer in humans and in white populations, 80-90% of them are due to exposure to sunlight. The three major types of skin cancer are the highly curable basal cell and squamous cell carcinomas and the highly malignant cutaneous melanoma. By protecting the skin from UV-light, sunscreens should be expected to prevent skin cancer, and public health authorities in many countries have advocated use of sunscreens for skin cancer prevention. But there are problems.
The scientific evidence concerning the impact of sunscreens on the development of skin cancer was evaluated by an International Working Group of experts convened by the International Agency for Research on Cancer of the World Health Organization (WHO), in Lyon, France. The Working Group concluded that the appropriate use of sunscreens probably prevents squamous cell carcinoma, the most frequent type of skin cancer, which mainly develops at exposed sites (face, arms and hands).
For malignant melanoma, which is characterized by metastatic spread to other organs, often with fatal consequences, the impact of sunscreen use is more complex. Several relevant epidemiological studies have shown significantly higher risks for melanoma in users of sunscreens than in non-users. This paradoxical observation could in part be due to the fact that users of sunscreens deliberately spend more time in the sun than they would otherwise have done. Thus, the protective effect of sunscreens can be outweighed by overexposure based on the false assumption that sunscreens completely abolish the adverse effects of UV-light.
In light of these findings, the Working Group concluded that sunscreens prevent sunburns and may reduce the risk of squamous cell carcinoma, but only if they do not mislead people to extend their exposure to sunlight. The Working Group also put forward several recommendations in relation to the use of sunscreens. Principal amongst these is that use of sunscreens should be one part of a comprehensive sun avoidance strategy that includes moving into shade when the sun is near zenith and the use of protective clothing. As part of a comprehensive skin protection strategy, sunscreens with a protection factor of 15 or more should be used.
For more information, please see the Working group's recommendations and overall evaluation, or contact Dr Nicolas Gaudin, Chief, IARC Communications (