Cutaneous melanoma in Iceland: changing Breslow's tumour thickness

Abstract

Background: The incidence of cutaneous melanoma increased dramatically in Iceland during the last two decades of the 20th century.

Objective: The aim of this study was to investigate the trend in Breslow's tumour thickness during the years 1980-2009.

Methods: The population-based Icelandic Cancer Registry provided information on all cutaneous melanomas diagnosed in the country during the study period, a total of 854 cases. Incidence rates were stratified according to gender, age at diagnosis, year of diagnosis and Breslow's tumour thickness.

Results: When stratified by gender and age, the incidence of thin (≤1.0 mm) melanomas increased dramatically in all subgroups. The increase in thin (≤1.0 mm) melanomas was more apparent in women or 2.6 per 100,000 in 1980-1989 to 13.3 in 2000-2009 and especially in young (<50 years) women or from 1.6 to 12.2 per 100,000 during the same period compared to an increase from 0.2 to 3.4 per 100,000 for young (<50 years) men (P < 0.05). In intermediate thickness (1.01-4.0 mm) tumours, the incidence increased only in men over the age of 50 from 2.1 in 1980-1989 to 11.3 per 100,000 in 2000-2009 (P < 0.05). The incidence of thick melanomas (>4 mm) did not increase. The median Breslow's thickness declined from 2.15 mm in 1980-1989 to 0.9 mm in 2000-2009 in males and from 1.0 to 0.6 mm in females for the same period (P < 0.001).

Conclusion: The rise in melanoma incidence in individuals under 50 years and in women over 50 years was confined to thin tumours. However, among older males there was also an increased incidence of tumours of an intermediate thickness. This could indicate that future melanoma educational campaigns in Iceland should be directed at older individuals, and that older men may need special attention regarding suspicious nevi.