PHENOTYPIC MARKERS, SUNLIGHT-RELATED FACTORS AND SUNSCREEN USE IN PATIENTS WITH CUTANEOUS MELANOMA - AN AUSTRIAN CASE-CONTROL STUDY

Sunscreens have been advocated to prevent burning in the hope that thi s will decrease the chance of developing melanoma. In a single-centre case-control study in Styria, Austria, we examined the risk of cutaneo us malignant melanoma in relation to phenotypic markers, sunlight-rela ted factors and sunscreen use. In total, 193 melanoma patients and 319 control subjects answered a comprehensive questionnaire regarding phe notypic markers, a variety of sunlight-related factors and sunscreen u se. Risk factors for melanoma were examined through the use of uncondi tional logistic regression analysis, controlling for age and sex. Scre ening for confounding factors was done by forward and backward elimina tion of non-significant variables (P < 0.05). The resulting set of fac tors were investigated further for effect modification by introducing interactions into the model. The factor most significantly associated with increased melanoma risk was the use of sunscreens. Subjects who o ften used sunscreens had an increased odds ratio (OR) of 3.47 (95% con fidence interval [CI]1.81-6.64) compared with subjects who never used sunscreens (P = 0.001), after adjustment for sex, age and other signif icant sunlight-related factors. Skin colour and higher numbers of sunb aths were significant protective factors. Subjects with medium skin co lour had an adjusted OR of 0.63 (95% CI 0.41-0.99) compared with subje cts with light skin colour (P = 0.0022). Subjects who took more than 3 0 sunbaths per year and subjects who took 20-30 sunbaths per year had, in the absence of sunburn(s), a decreased OR of 0.09 (95% CI 0.02-0.3 9) and 0.28 (95% CI 0.13-0.64), respectively, compared with subjects w ho took less than 20 sunbaths per year (P = 0.0002). However, sunbaths had no protective value when they were associated with sunburns. Alth ough we cannot exclude the presence of an unknown confounding factor, our results suggest that the use of sunscreens does not help prevent m elanoma. (C) 1998 Lippincott Williams & Wilkins.