Melanoma burden by melanoma stage: Assessment through a disease transition model

Background The total burden of melanoma has already been studied but little is known about the distribution of this burden amongst localised, node metastatic and distant metastatic stages.
Methods Disability-adjusted life years (DALY) assesses disease burden, being the sum of years of life with disability (YLD) and years of life lost (YLL). A melanoma disease model was developed in order to predict the evolution of patients from diagnosis until death. The model was applied to a large cohort of 8016 melanoma patients recorded by the Belgian Cancer Registry for incidence years 2009-2011. DALYs were calculated for each American Joint Committee on Cancer stage, considering stage at diagnosis on the one hand and time spent in localised, node metastatic and visceral metastatic stages on the other. Probabilistic sensitivity analyses and scenario analyses were performed to explore uncertainty.
Findings Our analyses resulted in 3.67 DALYs per melanoma, 90.81 per 100,000 inhabitants, or 32.67 per death due to melanoma. The total YLL accounted for 80.4% of the total DALY. Stages I, II, III and IV patients at diagnosis generated, respectively, 27.8%, 32.7%, 26.2% and 13.3% of the total YLL. For the time spent in each stage, localised melanomas, node metastatic melanomas, and distant metastatic accounted, respectively, for 34.8%, 52.6% and 12.6% of the total YLD. Parametric uncertainty was very limited, but the influence of using pre-2010 Global Burden of Disease approaches was substantial.
Interpretation The total DALY for melanoma was consistent with the previous studies. Our results in terms of proportions of DALY/YLL/YLD per stage could be extrapolated to other high-income countries. YLDs generated by localised melanoma which will never metastasize were inferior to YLLs resulting from stage IA melanomas. This result supports the hypothesis that efforts for an earlier diagnosis of melanoma are important. Funding None.