The CancerWeb Report, What's New In Cancer: July, 1996
Skin Cancer

• Sun exposure and skin characteristics as risk factors (Helios Study) - Previous studies in the US, Europe and Australia have established sun exposure and light complexion/hair color as risk factors for non-melanoma skin cancer - basal cell (BCC) and squamous cell (SCC) carcinomas. A large study (called Helios) carried out in Italy, France and Spain, and reported in the June, 1996 issue of the British Journal of Cancer used a wide range of physical types to provide with much new data. These researchers studied 1,549 cases of BCC and 228 cases of SCC, and 1,795 controls. With the standard risk (odds ratio) set at 1.0 for black hair and dark eyes, the risk for SCC varied from 1.7 for fair hair to 12.5 for red hair. The risk for BCC was 2.0 for light-blonde hair, while for those with pale eye color, the risks were 1.8 and 1.4 for SCC and BCC, respectively. Those who always burn and never tan had odds ratios of 2.7 for BCC and 2.0 for SCC. In those who burn and had sunburn at a young age the risk was increased for BCC but not SCC. In terms of sun exposure, the risk for SCC increased significantly with lifetime exposure exceeding a threshold of 70,000 cumulative hours, reaching 8 or 9 for 200,000 hours. There was a 2-fold increased risk of BCC for 8,000 to 10,000 hours exposure. SCC risk was significantly related to outdoor work involving long-term exposure, whereas BCC was associated more with intermittent recreational exposure, with increased risk after only 2,600 hours cumulative total. Ability to tan modulated the risk for BCC. (Zanetti, Br J Cancer 73:1440, 1996; Rosso, Br J Cancer 73:1447, 1996)

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• Ultraviolet light from lighting, sunlamps, and sunbeds and skin cancer - The connection between the ultraviolet (UV) component of sunshine and skin cancer, both melanoma and non-melanoma, is becoming clear, but what of UV from artificial sources? Tanning salons are increasing in number, as are a variety of other UV sources, and while a number of studies have shown that sunlamps increase the risk of melanoma, the effect on non-melanoma skin cancer has not been examined. A study carried out in Vancouver and Edmonton, Canada, and reported in the British Journal of Cancer, found no evidence of an association of this disease with exposure to various types of non-solar UV. They performed what is known as a case-control study, age-matching 226 cases of basal cell carcinoma and 180 cases of squamous cell carcinoma with 406 controls, and found no increased risk for either cancer with exposure during a 20-year period to fluorescent lighting at work, sunlamps (risk raised slightly but without statistical significance), welding torches, mercury vapor lamps, printing or photocopying lights, black lights, therapeutic UV lamps or horticultural growth-promoting lights. (Bajdik, Br J Cancer 73:1612, 1996)

  Editor's Comment: - Although reassuring that there are no major risks, this is a relatively small study, with only 8-10% of cases and controls ever exposed to sunlamps, for example. The authors themselves considered the numbers exposed to horticultural and black lights to be too small for reliable risk estimates. Limiting the duration and number of sunlamp exposures would still appear to be judicious, especially in view of the findings of the major Helios study of sun exposure, also presented in this month's CancerWeb Report.

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• Numbers and types of moles and cutaneous melanoma - The atypical mole syndrome, in which individuals have a large number of moles (naevi) typical and atypical, has been well studied in families with genetic susceptibility to melanoma. Atypical naevi tend to be irregular in shape and/or coloration, and are recognized precursors of melanoma. The syndrome also occurs sporadically in individuals with no family history of melanoma, and researchers at the London Hospital Medical school and the Imperial Cancer Research Fund, England, looked at this. Working with 426 cases of skin melanoma and 416 matched controls, they found that those with four or more atypical naevi had an almost 30-fold increased risk of developing melanoma, and there was a 10-fold risk for those with the atypical mole syndrome. Even a large number of ordinary moles was a risk factor, with a 7-fold increase for those with 100 or more naevi 2 mm or more in size. For unknown reasons, the atypical mole syndrome was significantly more common in those aged less than 40. (Bataille, Br J Cancer 73:1605, 1996)