Pigmentary traits, modalities of sun reaction, history of sunburns, and melanocytic nevi as risk factors for cutaneous malignant melanoma in the Italian population: results of a collaborative case-control study.

BACKGROUND To the authors' knowledge, limited data are available from Mediterranean populations concerning risk factors for malignant melanoma. A few Italian case-control studies have produced conflicting results regarding the association between malignant melanoma and pigmentary traits, sunburns, and melanocytic nevi. METHODS A case-control study was conducted within the framework of the Italian Group for Epidemiologic Research in Dermatology (GISED). Twenty-seven centers in the north and south of Italy participated. A total of 542 cases and 538 controls were entered onto the study. A standardized questionnaire was administered to cases and controls. Cases and controls also were examined by trained dermatologists who were required to count the number of melanocytic nevi (those measuring > or = 2 mm and > 6 mm in greatest dimension, separately) and to make judgments regarding pigmentary traits. RESULTS In the multivariate analysis, eye and skin color, propensity to sunburn, history of sunburns before age 15 years, and solar lentigines all were associated with malignant melanoma. In addition, the risk of melanoma increased with the number of melanocytic nevi > or = 2 mm. Nevi > 6 mm in greatest dimension had effects on risk that appeared to be independent from the effects of smaller nevi (2-6 mm). CONCLUSIONS The results of the current study largely are similar to those obtained in northern European countries, the U.S., and Australia and provide further evidence of the importance of selected pigmentary traits, sun exposure, and the number of melanocytic nevi in the risk of cutaneous malignant melanoma.