A Prospective Study of Pigmentation, Sun Exposure, and Risk of Cutaneous Malignant Melanoma in Women
Journal of the National Cancer Institute
A Prospective Study of Pigmentation, Sun Exposure, and Risk of Cutaneous Malignant Melanoma in Women
Marit Bragelien Veierød ) 0
Elisabete Weiderpass 0
Magnus Th o¨rn 0
Johan Hansson 0
Eiliv Lund 0
Bruce Armstrong 0
Hans-Olov Adami 0
0 Affiliations of authors: M. B. Veierød, Section of Medical Statistics, Univer- sity of Oslo , Oslo , Norway; E. Weiderpass, Department of Medical Epidemiol- ogy and Biostatistics, Karolinska Institutet, Stockholm, Sweden, and Interna- tional Agency for Research on Cancer , Lyon , France; M. Tho ̈rn, Department of Surgery, South Stockholm General Hospital , Stockholm; J. Hansson , Depart- ment of Oncology and Pathology, Karolinska Institutet; E. Lund, Institute of Community Medicine, University of Tromsø , Tromsø , Norway; B. Armstrong , School of Public Health, University of Sydney , Sydney , Australia; H.-O. Adami, Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, and Department of Epidemiology, Harvard University , Boston, MA. University of Oslo , P.O. Box 1122 Blindern, N-0317 Oslo , Norway (
Background: Although sun exposure is an established cause of cutaneous malignant melanoma, possible interactions with host factors remain incompletely understood. Here we report the first results from a large prospective cohort study of pigmentation factors and sun exposure in relation to melanoma risk. Methods: The Women's Lifestyle and Health Cohort Study included 106 379 women from Norway and Sweden who were aged 30-50 years in 1991 or 1992 when they completed an extensive questionnaire on personal characteristics and exposures. Linkages to national registries ensured complete follow-up through December 31, 1999. Poisson regression models were used to estimate relative risks (RRs). All statistical tests were two-sided. Results: During an average follow-up of 8.1 years, 187 cases of melanoma were diagnosed. Risk of melanoma was statistically significantly associated with increasing body surface area (RR for 1.79 m2 versus 1.61 m2 = 1.60, 95% confidence interval [CI] = 1.03 to 2.48; Ptrend = .02), number of large asymmetric nevi on the legs (RR for 7 nevi versus 0 nevi = 5.29, 95% CI = 2.33 to 12.01; Ptrend<.001), hair color (RR for red versus dark brown or black = 4.05, 95% CI = 2.11 to 7.76; Ptrend<.001), sunburns per year at ages 10-19, 20-29, and 30-39 years (Ptrend<.001, Ptrend = .03, and Ptrend = .05, respectively), and use of a device that emits artificial light (solarium) one or more times per month (P = .04). Conclusions: Our results confirm previous findings that hair color, number of nevi on the legs, and history of sunburn are risk factors for melanoma and suggest that use of a solarium is also associated with melanoma risk. Adolescence and early adulthood appear to be among the most sensitive age periods for the effects of sunburn and solarium use on melanoma risk. However, it may be too early to see the full effect of adult exposures in this cohort. [J Natl Cancer Inst 2003;95:1530-8] Cutaneous malignant melanoma (hereafter called melanoma) imposes a considerable public health burden. The incidence of melanoma varies more than 150-fold around the world, with the highest rates occurring among white or predominantly white populations in Australia, New Zealand, North America, and northern Europe (1). Rates of melanoma in Norway and Sweden have more than tripled since 1958-1962, the first years that
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reliable information was available from cancer registries; rates
are now higher there than they are elsewhere in Europe (2) and
are predicted to increase (3).
Although sun exposure is the major established risk factor for
melanoma (4,5), geographic differences in melanoma incidence
cannot be attributed solely to differences in the intensity of solar
exposure. Within Europe, for example, the incidence of
melanoma is higher at northern latitudes, which generally have lower
solar intensities, than at southern latitudes, which generally have
higher solar intensities (2), although in both Norway and
Sweden, an inverse relationship between melanoma incidence and
latitude has been noted (6,7). Hence, the effect of UV light on
melanoma risk may be strongly modified by other factors, such
as differences in sun sensitivity and the nature of the exposure to
the sun (8).
A number of studies have examined factors that influence the
association between sun exposure and the risk of melanoma. An
intermittent pattern of sun exposure, which is typically assessed
by measures of sun-intensive activities, such as outdoor
recreation or vacations, is associated with increased risk of melanoma
(9). In addition, many studies (4,5,9,10) have reported that
sunburn, which is an indicator of an intermittent pattern of sun
exposure, is positively associated with the risk of melanoma.
Results of many studies have suggested that childhood is a
critical period for sun exposure (9), and ecologic studies have shown
more cons (...truncated)