Sex differences in rising trends of cutaneous malignant melanoma in Norway, 1954-2008.

With more than a seven-fold increase during the last 50 years, the incidence rate of cutaneous malignant melanoma in Norway is amongst the highest worldwide. The present study aims to present the incidence trends of cutaneous malignant melanoma in Norway, 1954-2008, according to period, sex, age, stage of disease, anatomical location and geographical regions, and discuss the results in relation to sun exposure habits over time. All new cases of invasive cutaneous malignant melanoma diagnosed in the Norwegian population between 1 January 1954 and 31 December 2008 were retrieved from the Cancer Registry of Norway (n=31 783). In addition to descriptive analyses, joinpoint and age-period-cohort regression models were used to explore the incidence trends. Throughout the 1980s, a steep increase in the rate of melanoma was observed in both sexes, continuing to increase from the late 1990s. Age-specific incidence rates showed the steepest increase in age groups older than 50 years, and were most pronounced in men. A clear sex-specific anatomical distribution exists, although the trunk has become the most common location for both sexes. During the entire period of follow-up, a two-fold risk was observed in inhabitants of the southern compared with the northern part of Norway. It is reasonable to suggest that the rising incidence rates of melanoma in Norway, in both sexes, reflect a strengthened intermittent sun exposure pattern over time. The particularly strong incidence increase in older men corresponds with their less favourable sun-protective behaviour.