Outdoor activities in childhood: a protective factor for cutaneous melanoma? Results of a case-control study in 271 matched pairs

Background A matched case–control study was performed in Munich, Germany, in 1996–97 to evaluate the risk of cutaneous melanoma due to ultraviolet (UV) exposure behaviour in Southern Bavaria, Germany. Objectives Patients with cutaneous melanoma and controls were investigated by two physicians using a standardized questionnaire to identify risk factors for the development of melanoma, such as professional and leisure sun exposure behaviour. In each person, a total body examination was performed to detect benign skin alterations, phenotypic characteristics and precursor lesions for skin cancer. Patients/methods A total of 271 melanoma patients and 271 controls were individually matched for residence, age and gender. A multiple conditional logistic regression analysis was performed. Results Of 56 factors, those risk factors with a strong effect on the development of melanoma were: the existence of melanoma in first degree relatives, solar lentigo, actinic keratosis, actinic cheilitis, skin phototype, immediate skin reaction to UV light at the start of the outdoor season, sunburn in childhood and sun exposure during holidays in sunny areas 20 years before melanoma was diagnosed; outdoor activities in childhood were found to be protective. Conclusions Sunburn in childhood and increased sun exposure during annual holidays in sunny areas should be avoided. In contrast, outdoor activities in childhood, including soccer and gardening, should be encouraged because they are associated with a lower risk of melanoma formation.