Bring Me Sunshine

4 June 2008

Sunshine has had a bad press recently. However a new study shows that insufficient exposure to ultraviolet radiation may be an important risk factor for cancer in western Europe and North America. When US mortality rates for cancer were examined, it was found that a range of cancers of the digestive and reproductive systems in New England were close to double those in the south west US, despite only minor variations in dietary habits. Looking at 506 different regions of the US it was found that there was a close inverse correlation between cancer mortality and levels of ultraviolet B light. It is suggested that the protective effect of sunlight is a stimulus to the body to synthesise vitamin D. The strongest correlation with lack of sunlight was found with cancers of the breast, colon, and ovaries.

Other cancers seemingly affected by sunlight include the bladder, uterus, oesophagus, rectum, and stomach. The study suggests that around 85,000 additional cancers and 30,000 additional deaths will be attributable to lack of sunlight in the year 2002. At the same time the total number of additional deaths from melanoma and other skin cancers that would occur with uniform exposure across the US to sunlight equivalent to the south west would be about 3000. The authors suggest that the sun exposure debate has been overly dominated by dermatologists. (Cancer 2002;94:1867-75) In an earlier study, 25% of cases of breast cancer in 35 European countries were attributed to insufficient exposure to ultraviolet B. (Cancer 2002;94:272-81).

The use of sunlamps and sunbeds is associated with a 2.5-fold increase in basal cell carcinoma (BCC) and a 1.5-fold increase in squamous cell carcinoma (SCC), both risks independent of age, sex, sun sensitivity and extent of natural sun exposure. Notably the risks increased by 20% for BCC and 10% for SCC for every decade the patient was younger at first use of artificial tanning devices (J Natl Cancer Inst 2002; 94: 224-226).

: Lifestyle

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