RECREATIONAL EXPOSURE TO SUNLIGHT AND LACK OF INFORMATION AS RISK-FACTORS FOR CUTANEOUS MALIGNANT-MELANOMA - RESULTS OF AN EUROPEAN-ORGANIZATION-FOR-RESEARCH-AND-TREATMENT-OF-CANCER (EORTC) CASE-CONTROL STUDY IN BELGIUM, FRANCE AND GERMANY

This study addressed the impact of exposure to ultraviolet radiation on the risk of cutaneous malignant melanoma (CMM), as well as the behavioural components at stake in its occurrence. We performed a one-to-one unmatched case-control study among subjects aged 20 years or more with naturally non-pigmented skin in Germany, France and Belgium. Four-hundred and twenty consecutive patients with CMM diagnosed from 1 January 1991 on were derived from hospital registries; 447 controls were chosen ramdomly in the same municipality as cases. Subjects unaware of the dangers of exaggerated exposure to sunlight display an estimated CMM risk of 3.72 (95% confidence interval 2.63-5.26). The number of holiday weeks spent annually in sunny resorts and sunbathing during the hot hours of the day are strong risk factors in the three countries, but not the number of years spent outdoors, as farmers or building workers. Multiple logistic adjustments on the host characteristics increases the CMM risk associated with recreational exposure to sunlight, as well as the adjustment on the unawareness of the dangers of exaggerated exposure to sunlight. Recreational exposure to sunlight and sunburn early in life seem capable of fostering the proliferation of pigmented lesions of the skin. Our data support the hypothesis that most CMM develop from pigmented lesions of the skin containing initiated melanocytes, and that the cell proliferation due to brutal, intermittent exposures to solar radiation amplifies the likelihood of a melanocyte entering into a malignant process. These results reinforce the conviction that for controlling the rising incidence of CMM, information about the CMM risk must be widely disseminated, mainly through recommending a prudent attitude towards exposure to sunlight.