Is sun exposure a major cause of melanoma? NoBMJ 2008; 337 doi: http://dx.doi.org/10.1136/bmj.a764 (Published 22 July 2008) Cite this as: BMJ 2008;337:a764
- Sam Shuster, honorary consultant
- 1Department of Dermatology, Norfolk and Norwich University Hospital, Norwich NR4 7UY
The list of harmful things grows daily, freshly mined by descriptive epidemiology, a substitute for research that confuses association with cause. Although most disappear under the weight of their own inconsequence, the alleged increase in melanoma from ultraviolet radiation has survived on the life support of regular promotion. I am therefore setting out what is known, which is rather different from what is believed.
Does ultraviolet light cause melanoma?
There is solid descriptive, quantitative, and mechanistic proof that ultraviolet rays cause the main skin cancers (basal and squamous). They develop in pale, sun exposed skin,1 are related to degree of exposure and latitude,2 are fewer with avoidance and protection,3 4 are readily produced experimentally,4 and are the overwhelmingly predominant tumour in xeroderma pigmentosum, where DNA repair of ultraviolet light damage is impaired.
None of these is found with melanoma. Variation is more ethnic5 6 7 than pigmentary,8 and 75% …
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