[Risk factors for the development of malignant melanoma and identification of risk groups in German-speaking regions].

Risk factors for development of malignant melanoma have been investigated in several case control studies during the last decade, with some variation in results, partly with geographical region. Four studies have been conducted under the auspices of the Central Malignant Melanoma Registry of the German Dermatological Society; these have yielded consistent results allowing the identification of risk factors for melanoma development. The numbers of common melanocytic naevi, of atypical melanocytic naevi and the frequency of actinic lentigines were found by multivariate regression analysis to be the most important independent risk factors for melanoma development. Additional factors were hair colour, skin type and a history of naevus growth. A classification of relative risks was established by considering the first three risk factors mentioned, without any clear improvement of classification when further additional significant factors were taken into account. For example, in individuals with more than 50 common melanocytic naevi, 5 or more atypical melanocytic naevi and simultaneous presence of actinic lentigines the risk of developing melanoma was found to be 100-fold that in persons with 10 common melanocytic naevi or fewer and without atypical melanocytic naevi or actinic lentigines. Early recognition of melanomas may be substantially improved if these risk factors are considered. Furthermore, intermittent intensive sun exposure (sunburns as indicator) before the age of 20 induces the development of actinic lentigines; both factors are associated with an increased risk of melanoma development.