A recent paper by Boniol and colleagues estimates that sunbed use in 18 European countries accounts for 1096 (986-1224) cases of melanoma/year for men and 2341 (2107-2614) cases/year for women in 2008.1 I commented on this paper in a posting at the journal website.2 This blog is a summary of that comment, with some additional points.
It should be noted that this was a review of observational studies and many confounding factors such as skin type, solar UV exposure, and type of UV lamp (tanning facility, home, or medical office) were not always included in the individual studies. In addition, observational studies are not generally accepted by the health or medical community as proving causality. In fact, many of the same authors largely rejected observational studies of beneficial effects of vitamin D in reducing risk of cancer, although allowed that findings for colon cancer were reasonably strong.3
A more important question in melanoma risk is death from melanoma. The mortality rate can be estimated by the ratio of melanoma deaths to cases in the 27 countries of the European Union, available from GLOBOCAN.4 Assuming that the EU-18 used in Ref. 1 account for 71% of both cases and deaths, there would be 186 (95% CI, 167-208) melanoma deaths for men and 304 (274-339) deaths for women in 2008.
Any evaluation of whether something should be used should also estimate benefit. This was not done in Ref. 1. Sunbeds are a good source of vitamin D, producing at least 10,000 IU in a single session.5 There are about 15 types of cancer for which solar ultraviolet-B (UVB) irradiance has been found inversely correlated with incidence or mortality rate in ecological studies.6 Vitamin D production is the only mechanism suggested to explain the findings.
An estimate of the benefits in reducing risk of internal cancers can be made using findings of cancer incidence in Sweden for women with respect to use of sunbeds.7 Ref. 7 had information on sunbed use for 37,940 women. For the 26.2% of the women who used sunbeds rarely but not >1 time/month in any decade, 10-39 years, the hazard ratio for breast cancer was 0.81 (0.68-0.96) (i.e., 19% reduction) while that for overall cancer was 0.89 (0.79-1.00) (i.e., 11% reduction).
The estimates for breast cancer and overall cancer can be estimated assuming that 16% of men and 26% of women used sunbeds in the amount used from Ref. 7 based on a study of sunbed use in Germany.8 Breast cancer cases and deaths for the 18 European countries can be estimated from the data in Ref. 4 assuming that 71% of the cases and deaths are from the 18 countries included in Ref. 1. The estimate of reductions in cases in 2008 is 11,668 (19,652-3703) and that for deaths is 3151 (663-5307). For overall cancer, the estimates for reductions is 16,554 (0-31,602) cases and 8667 (0-16,547) deaths for men and 22,740 (0-43,414) cases and 11,265 (0-20,960) deaths. The benefit-to-risk ratio based on overall cancer deaths to melanoma deaths is 47:1 for men and 37:1 for women. Since there are many other health benefits of vitamin D9, the overall benefit-to-risk ratios are much higher.
There have been several papers reporting health benefits of sunbed use including higher bone mass density10, reduced risk of thrombotic events11, and reduced risk of endometrial cancer12.
It should also be noted that the role of UV in risk of melanoma is complex. Those who have chronic UV exposure do not have higher risk of melanoma than others13-15.
Solar UVB light is the primary source of vitamin D for most people. In winter at high latitudes, it is impossible to make vitamin D from solar UVB16. One source for vitamin D in winter is artificial UVB as from sunbeds. An alternative source of vitamin D is high-dose (1000-5000 IU) vitamin D3 supplements.
1.Boniol M, Autier P, Boyle P, Gandini S. Cutaneous melanoma attributable to sunbed use: systematic review and meta-analysis. BMJ 2012;345:e4757.
2. Grant WB. Re: Cutaneous melanoma attributable to sunbed use: systematic review and meta-analysis. BJM July 25, 2012 http://www.bmj.com/contenT/345/bmj.e4757?tab=responses
3. IARC Working Group Report 5: Vitamin D and Cancer. IARC, Lyon, France (Nov. 25, 2008)
4. Ferlay J, Shin HR, Bray F, Forman D, Mathers C, Parkin DM. Estimates of worldwide burden of cancer in 2008: GLOBOCAN 2008. Int J Cancer. 2010;127:2893-917. http://globocan.iarc.fr/factsheet.asp
5. Moan J, Lagunova Z, Cicarma E, Aksnes L, Dahlback A, Grant WB, et al. Sunbeds as vitamin D sources. Photochem Photobiol. 2009;85:1474-9.
6. Grant WB. Ecological studies of the UVB–vitamin D–cancer hypothesis; review. Anticancer Res. 2012;32:223-36.
7. Grant WB. Relation between prediagnostic serum 25-hydroxyvitamin D level and incidence of breast, colorectal, and other cancers. J Photochem Photobiol B. 2010;101:130–6.
8. Yang L, Veierød MB, Löf M, Sandin S, Adami HO, Weiderpass E. Prospective study of UV exposure and cancer incidence among Swedish women. Cancer Epidemiol Biomarkers Prev. 2011;20:1358-67.
9. Schneider S, Zimmermann S, Diehl K, Breitbart EW, Greinert R. Sunbed use in German adults: risk awareness does not correlate with behaviour. Acta Derm Venereol. 2009;89:470-5.
10. Grant WB. An estimate of the global reduction in mortality rates through doubling vitamin D levels. Eur J Clin Nutr. 2011;65:1016-26.
11. Tangpricha V, Turner A, Spina C, Decastro S, Chen TC, Holick MF. Tanning is associated with optimal vitamin D status (serum 25-hydroxyvitamin D concentration) and higher bone mineral density. Am J Clin Nutr. 2004;80:1645-9.
12. Lindqvist PG, Epstein E, Olsson H. Does an active sun exposure habit lower the risk of venous thrombotic events? A D-lightful hypothesis. J Thromb Haemost. 2009;7:605-10.
13. Epstein E, Lindqvist PG, Geppert B, Olsson H. A population-based cohort study on sun habits and endometrial cancer. Br J Cancer. 2009;101:537-40.
14. Chang YM, Barrett JH, Bishop DT, Armstrong BK, Bataille V, Bergman W, et al. Sun exposure and melanoma risk at different latitudes: a pooled analysis of 5700 cases and 7216 controls. Int J Epidemiol. 2009;38:814-30.
15. Newton-Bishop JA, Chang YM, Elliott F, Chan M, Leake S, Karpavicius B, et al. Relationship between sun exposure and melanoma risk for tumours in different body sites in a large case-control study in a temperate climate. Eur J Cancer. 2011;47:732-41.
16. Grant WB. Role of solar UV irradiance and smoking in cancer as inferred from cancer incidence rates by occupation in Nordic countries. Dermatoendocrinol. 2012;4(2) epub
17. Webb AR, Engelsen O. Calculated ultraviolet exposure levels for a healthy vitamin D status. Photochem Photobiol. 2006;82:1697-703.