K. R. Stephens1, W. Donica1, P. Philips1, K. McMasters1, M. E. Egger1 1University Of Louisville, Division Of Surgical Oncology, Department Of Surgery, Louisville, KY, USA
Introduction: The majority of melanomas diagnosed in the US are thin, low risk lesions with a Breslow thickness < 1.0 mm. However, previous population studies have suggested that the majority of deaths from melanoma are in these low risk, thin lesion patients because of the absolute number of thin lesions that are diagnosed compared to other higher risk lesions. However, regional and metastatic disease were excluded in these analyses. The aim of this study was to evaluate the relative proportion of melanoma-related deaths across all stages at diagnoses in thin, intermediate, and thick melanomas.
Methods: A review of all cutaneous melanoma cases in the US SEER database from 2004-2020 was performed. Thickness was categorized according to AJCC 8th edition T group criteria. Primary tumor thickness and stage at diagnosis were compared for all-cause deaths and melanoma-specific mortality. The cumulative incidence of melanoma-specific death was estimated using Kaplan-Meier survival analysis, with non-melanoma deaths considered as a competing risk.
Results: From 2004 to 2020, 260,798 first primary melanoma cases were identified. Overall, there were 23,747 deaths attributed to melanoma; there were 15,470 melanoma-specific deaths with all available thickness and staging data available for analysis. Most melanoma deaths were in patients who initially presented with local disease (53%) compared to regional (36%) or distant (11%) disease, p < 0.001. However, the majority of the melanoma-specific deaths in patients who presented with localized disease were in those with intermediate or thick (thickness ≥ 1.0 mm) primary tumors (70% of all localized melanoma-specific deaths) compared to those with a thin melanoma (30% of all localized melanoma-specific deaths), Figure 1. Patients with localized disease at the time of diagnosis with a thin primary tumor only accounted for 16% of melanoma-specific deaths in the entire cohort. Most of the annual deaths in patients with thin melanomas were from other causes (80-90%), while the causes of death in the intermediate/thick melanoma patients were equally as likely to be from melanoma and non-melanoma causes. The cumulative incidence of death at 10 years in patients with localized, thin melanoma at the time of diagnosis was 2.4% (95% CI 2.3-2.5%).
Conclusion: Most deaths attributable to melanoma are indeed in patients who are initially diagnosed with localized melanoma. However, these deaths are overwhelming associated with intermediate/thick melanomas (≥ 1.0 mm), not thin melanomas. The public health burden in terms of death from melanoma is in this higher risk localized group, in addition to those with advanced regional and metastatic disease at diagnosis.
