Constitutional and environmental risk factors for cutaneous melanoma in an Italian population. A case-control study.

The aim of this study was to determine the relative risk for cutaneous melanoma associated with phenotypic and environmental variables in a population in central Italy and to assess how the combination of the different risk factors contributes to the overall risk for melanoma. We performed a case-control study of 100 patients with sporadic cutaneous melanoma and 200 controls matched for sex, age, ethnicity and residential area. Individuals were interviewed concerning pigmentary traits and sun exposure, and underwent a total body skin examination. Logistic regression models were used to evaluate the association between cutaneous melanoma and constitutional and environmental variables. The strongest risk factors were prolonged recreational sun exposure (odds ratio [OR] 5.010, 95% confidence interval [CI] 2.110-11.891), the presence of clinically atypical naevi (OR 4.916, 95% CI 2.496-9.995) and the presence of >50 common melanocytic naevi (OR 4.684, 95% CI 2.442-9.231). In addition, occupational sun exposure (OR 2.573, 95% CI 1.399-4.732), light brown hair (OR 2.336, 95% CI 1.328-4.138), high density of solar lentigos and/or actinic keratoses (OR 1.824, 95% CI 1.0-3.510) and type II, fair skin (OR 1.815, 95% CI 1.031-3.193) and blue eyes (OR 1.757, 95% CI 1.0-3.477) were each significantly associated with cutaneous melanoma risk. The combination of individual strong risk factors was associated with up to a 46-fold increase in the risk for cutaneous melanoma. Selected pigmentary traits, sun exposure and melanocytic naevi, individually and in combination, are important risk factors for cutaneous melanoma in an Italian population.