Influence of socioeconomic factors and region of residence on cancer stage of malignant melanoma: a Danish nationwide population-based study.

Background: Socioeconomic differences in survival after melanoma may be due to late diagnosis of the disadvantaged patients. The aim of the study was to examine the association between educational level, disposable income, cohabitating status and region of residence with stage at diagnosis of melanoma, including adjustment for comorbidity and tumor type.

Methods: From The Danish Melanoma Database, we identified 10,158 patients diagnosed with their first invasive melanoma during 2008-2014 and obtained information on stage, localization, histology, thickness and ulceration. Sociodemographic information was retrieved from registers of Statistics Denmark and data on comorbidity from the Danish National Patient Registry. We used logistic regression to analyze the associations between sociodemographic factors and cancer stage.

Results: Shorter education, lower income, living without partner, older age and being male were associated with increased odds ratios for advanced stage of melanoma at time of diagnosis even after adjustment for comorbidity and tumor type. Residence in the Zealand, Central and Northern region was also associated with advanced cancer stage.

Conclusion: Socioeconomically disadvantaged patients and patients with residence in three of five health care regions were more often diagnosed with advanced melanoma. Initiatives to increase early detection should be directed at disadvantaged groups, and efforts to improve early diagnosis of nodular melanomas during increased awareness of the Elevated, Firm and Growing nodule rule and "when in doubt, cut it out" should be implemented. Further studies should investigate regional differences in delay, effects of number of specialized doctors per inhabitant as well as differences in referral patterns from primary to secondary health care across health care regions.