CORRESPONDENCE

RESPONSE: Re: Sunscreen Use and Duration of Sun Exposure: a Double-Blind, Randomized Trial

Philippe Autier, Remy Pedeux, Jean-Francois Doré, For The EORTC Melanoma Cooperative Group

Affiliations of authors: P. Autier, European Institute of Oncology, Milan, Italy; R. Pedeux, J.-F. Doré, Institut National de la Santé et de la Recherche Médicale, Centre Léon Bérard, Lyon, France.

Correspondence to: Philippe Autier, M.D., European Institute of Oncology, Division of Epidemiology and Biostatistics, Via Ripamonti 435, Milan 20141, Italy (e-mail: philippe.autier{at}ieo.it).

In their experiment, Hemminki et al. showed that a suntan offers little protection against UV-induced DNA damage. Because a tan moderately reduces the susceptibility to sunburn, acting similarly to the sunscreens used in our study (1), acquisition of a tan may encourage recreational sun exposure. Lengthening of sun exposure would largely overwhelm the minimal protection conferred by the tan, resulting in increased DNA damage and skin cancer risk. Furthermore, the results displayed in Fig. 1 of Hemminki et al. suggest that a tan would confer no protection against DNA damage induced by lower doses of UV radiation.

The experiment of Hemminki et al. is particularly relevant to the context of indoor tanning, since their study subjects were given 10-13 sessions of so-called UVA-tanning over a period of 3 weeks. Indoor tanning has become fashionable in North America and Europe, mainly among adolescents and young adults. Surveys in various fair-skinned populations show that 25%-50% of sunbed users report that they want to prepare their skin for holidays, apparently believing that acquisition of a tan before the start of a vacation confers protection against sunburns and other deleterious effects of the sun. A closer look at data from a study that we performed in Belgium, France, and Germany in 1991-1992 (2) showed that acquiring a tan was the principal reason given for sunbed use in the 1970s; citing sun protection as a motive for indoor tanning appeared in the 1980s. Before 1970, most exposure to artificial sources of UV light was occupational or medical (e.g., treating psoriasis or inducing vitamin D synthesis in Nordic countries) (2).

Messages of questionable scientific validity have spread the idea that a prevacation tan could be protective. The role of tanning in skin carcinogenesis remains unclear (3,4), but the tanning process seems to be a consequence of the UV-induced DNA damage (5). The experiment of Hemminki et al. supports the notion that a tan artificially acquired before holidays may promote prolonged sun exposure and thus may lead to increased DNA damage and skin cancer risk.

Although some epidemiologic data suggest that indoor tanning could increase the risk of melanoma, additional studies are needed to settle the issue (6). In any case, the experiment of Hemminki et al. indicates that the risks associated with indoor tanning would include not only the exposure to UV radiation emitted by tanning devices, but also the possibility of prolonging sun exposure during a subsequent holiday. Hence, in the light of available data, visiting tanning parlors before leaving for vacation is not advisable.

REFERENCES

1 Autier P, Dore JF, Negrier S, Lienard D, Panizzon R, Lejeune FJ, et al. Sunscreen use and duration of sun exposure: a double blind randomized trial. J Natl Cancer Inst 1999;91:1304-9.[Abstract/Free Full Text]

2 Autier P, Dore JF, Lejeune F, Koelmel KF, Geffeler O, Hille P, et al. Cutaneous malignant melanoma and exposure to sunlamps or sunbeds: an EORTC multicenter case-control study in Belgium, France and Germany. EORTC Melanoma Cooperative Group. Int J Cancer 1994;58:809-13.[Medline]

3 Barker D, Dixon K, Medrano EE, Smalara D, Im S, Mitchell D, et al. Comparison of the responses of human melanocytes with different melanin contents to ultraviolet B irradiation. Cancer Res 1995;55:4041-6.[Abstract]

4 Kvam E, Tyrrell RM. The role of melanin in the induction of oxidative DNA base damage by ultraviolet A irradiation of DNA or melanoma cells. J Invest Dermatol 1999;113:209-13.[Abstract/Free Full Text]

5 Pedeux R, Al-Irani N, Marteau C, Pellicier F, Branche R, Ozturk M, et al. Thymidine dinucleotides induce S phase cell cycle arrest in addition to increased melanogenesis in human melanocytes. J Invest Dermatol 1998;111:472-7.[Abstract]

6 Swerdlow AJ, Weinstock MA. Do tanning lamps cause melanoma? An epidemiologic assessment. J Am Acad Dermatol 1998;38:89-98.[Medline]



             
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