Melanoma and the sun: the effect of swimsuits and a "healthy" tan on the risk of nonfamilial malignant melanoma in women.

The authors examined the relation between sun exposure and melanoma risk and tested the previously published site-specific association of bikini use and melanoma of the trunk in a study of 130 cases incident between 1976 and 1984 and 300 controls nested within the Nurses' Health Study. A summary variable derived from four measures of sun sensitivity was more closely associated with melanoma than any component measure. There was no association of bikini use at ages 15-20 years with trunk melanoma risk (relative risk (RR) = 0.8, p = 0.7), and the 95% confidence interval (CI) (0.3-2.6) excludes the previously published estimate. High frequency of swimsuit use outdoors at ages 15-20 years was associated with increased melanoma risk among sun-sensitive women (RR = 6.4, 95% CI 1.7-23.8, p = 0.006), but appeared to be protective among sun-resistant women (RR = 0.3, 95% CI 0.1-1.0, p = 0.06). These findings suggest that the risk of trunk melanoma associated with bikini use is at most modest and that sun-sensitive women may increase their risk of melanoma with frequent sun exposures, but that sun-resistant women do not, presumably because they develop a photoprotective tan.