Melanoma of the external ear: A population-based study

Background Primary melanoma of the external ear (PMEE) is rare and therefore well-suited for large population-based registry analysis. The objective of this study was to utilize the Surveillance, Epidemiology, and End Results (SEER) set of cancer registries to determine the incidence, treatment, and survival characteristics of PMEE. Methods A retrospective cohort analysis of SEER data from 2004 to 2013 identified all cases of PMEE stage I-IV by AJCC 7th edition guidelines. Population-based incidence was calculated. Cancer-specific survival data by stage was assessed using Kaplan-Meier analysis and the relative effects of tumor characteristics were analyzed with Cox regression models. Results A total of 5481 patients were analyzed (mean age 66.7 years, 86.5% male, 93.6% non-Hispanic white). The incidence of PMEE was 1.91 per 100,000 persons-per-year. At diagnosis, 68.1% were stage I, 15.2% were stage II, 4.7% were stage III, 1.5% were stage IV, and 10.8% were unknown. The five-year overall and cancer-specific survival was 78.8% and 90.0%, and, according to AJCC stage, was 85.7% and 95.3% for stage I (n = 2287), 64.6% and 81.1% for stage II (n = 453), 50.8% and 57.0% for stage III (n = 154), 17.2% and 20.5% for stage IV (n = 34), and 71.0% and 87.1% for unknown stage (n = 330), respectively. The multivariable Cox model identified tumor characteristics that were independently associated with survival. Conclusions This is the first study to characterize the epidemiology, presentation and outcome of PMEE using the SEER registries. Older age, increasing Breslow thickness, stage, presence of ulceration, positive lymph nodes and distant metastasis each independently predicted time to cancer-specific death.