Cutaneous malignant melanoma show geographic and socioeconomic disparities in stage at diagnosis and excess mortality

Abstract

Background Preventive measures are needed to counteract the increasing burden of cutaneous malignant melanoma (CMM). As a basis for rational melanoma prevention, we investigated geographic differences and impact from socioeconomic factors related to incidence, clinical stage at diagnosis and outcome.

Material and methods All patients with primary invasive CMM diagnosed in 2004–2013 in the southern and the western Swedish health care regions with a population of 2.9 million adults were eligible for the study. Population-based data were obtained from the national Cancer Register and the national Melanoma Quality Register. Geographic and socioeconomic differences in incidence per stage at diagnosis were mapped and correlated to excess mortality.

Results Disease mapping based on 9743 cases in 99 municipalities and 20 metropolitan districts showed marked, regional disparities in stage-specific incidence of CMM. The incidence of stage I–II tumors was higher in the western health care region, whereas the incidence of stage III–IV CMMs was higher in the southern region. The divergent incidence patterns per stage at diagnosis were consistent across population strata based on educational level. The geographic disparities in CMM stage influenced relative survival with an excess five-year mortality ratio in the southern region versus the western region of 1.49 (95% confidence interval 1.22–1.82). The excess mortality ratio for patients with low versus high educational level was 1.81 (1.37–2.40).

Conclusion Residential region and educational level influenced CMM stage and, thereby, excess mortality. These observations suggest that geographic as well as socioeconomic data should be considered in prevention of CMM.