Objective: The aim of this study was to examine indirectly the importance of sun exposure during childhood and adolescence for the development of cutaneous malignant melanoma (CMM) by using a migration approach.
Methods: A nested case-control study was carried out based on all inhabitants living in Norway at any time between 1960 and 1980. The cases were all diagnosed between 1960 and 1992 (n = 13,934) and 10 controls were added for each case (n = 130,507). Analyses were conducted on residence history in the southeast, mid-west and northern part of Norway, before and after age 17, also including working condition and educational level.
Results: Birthplace in southeast was found to be twice as hazardous for the risk of CMM compared with birthplace in the north. The region of residence before as well as after age 17 was shown to influence the risk of CMM; the risk pattern in migrants tended to change direction toward the risk in the region to which they move. Associations was found between indoor working condition and CMM, and between high level of education and CMM, which support the hypothesis that pattern of sun exposure in adulthood affects the risk of CMM.
Conclusion: The results indicate sun exposure at any age to be of importance for the lifetime risk of CMM.