Newswise — The recent paper by Hemminki et al. reported interesting results on trends of squamous cell carcinoma (SCC) of the skin in Sweden, namely that there has been a significant increase in SCC for covered skin starting in the 1980s in addition to the increases in SCC in sun-exposed skin dating back to the 1960s. The interpretation provided was that the increase in SCC for covered skin was likely due to intentional tanning, both during trips abroad and in sun beds. No data on gender differences in trips abroad were presented, but it was pointed out that females use sun beds at twice the rate of males in Sweden. However, males have twice the rate as females for SCC for covered skin. Thus, it is very unlikely that intentional tanning explains the data.
A much more likely explanation can be found in the effects of smoking, a well-known risk factor for SCC and basal cell carcinoma. Smoking gives rise to SCC though carcinogens and free radicals, even for covered skin areas. There has been an increase in smoking deaths in Sweden between 1955 (1100 males, <100 females) and 1995 (1800 males, 900 females) and the 1995 sex ratio of smoking deaths is very similar to the sex ratio reported for SCC in covered skin. Also, the adverse effects of smoking generally happen later in life, as is the case for the SCC data reported. Recent ultraviolet (UV) radiation exposure practices would not yet be reflected in SCC data.
Thus, any study trying to link UV radiation, natural or artificial, to skin cancer and, perhaps, melanoma, should carefully consider the smoking habits of those studied, as well as dietary factors that may be involved in generating or fighting free radicals.
Contact: William B. Grant, Ph.D.,William B. Grant does independent health research from his office in Newport News, Virginia. His health work is primarily related to identifying and quantifying risk and risk reduction factors from dietary factors and UVB radiation for chronic diseases. He published the first paper linking diet to Alzheimer's disease in 1997 and has published a number of papers on diet and other chronic diseases and on the health benefits of solar UVB radiation and vitamin D. He is moving to San Francisco in April and will continue such work through Sunlight, Nutrition and Health Research Center (SUNARC).