Introduction: The incidence of melanoma of the skin has risen in Denmark in recent decades, the increase being steeper from 2004. It is unclear whether this represents a true rise in incidence or whether it is caused by an increased awareness of the condition.
Methods: To assess whether the increase was characterised by early-stage melanomas and a higher proportion of melanomas with superficial spreading morphology, we studied all skin melanoma patients registered in the Danish Cancer Register 1989-2011 (n=27,010) and followed up for death through 2013. Trends in age-standardised incidence by sex, subsite and morphology, relative survival, TNM stage distribution and stage-specific relative survival from 2004 were analysed.
Results: The incidence of melanoma more than doubled over 23 years. A steeper increase from 2004 was driven mainly by superficial spreading tumours, but the proportion of nodular melanomas in patients 50 years of age and over also increased significantly. The largest increase occurred for stage I tumours and for tumours on the trunk. From 1989-1993 to 2009-2011 the 5-year relative survival increased at 12% and 6% points for male and female patients, respectively.
Interpretation: Greater awareness, and thus lower stage at diagnosis (mediated by a large skin cancer prevention campaign from 2007), might explain part of the increase, but the increase in nodular melanoma also points to a genuine increase in the risk of melanoma.
Keywords: Cancer register; Epidemiology; Incidence; Melanoma; Risk factors; Superficial spreading morphology; Survival; TNM stage; Time trends.
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