LAUSR

Background: Thin melanomas cause a high death toll despite excellent prognosis. Objective: We examined melanoma mortality burden and prognosis by categories of thickness within Surveillance, Epidemiology, and End Results (SEER) 13 Registry 1992‐2013. Methods: We divided 49,319 stage I and II melanoma cases diagnosed between 1992 and 2003 into T1 through T4 and then subdivided T1 into 0.01‐0.25 mm, 0.26‐0.50 mm, 0.51‐0.75 mm, and 0.76‐1.00 mm categories. We determined the number and proportion of deaths due to melanoma within 10 years of diagnosis for each thickness category and proportions within T1 subcategories with ulceration. Results: We confirmed prognosis worsened as melanoma thickened from T1 to T4; however, most deaths resulted from melanomas that were diagnosed at the T1 stage. The smallest number of deaths within T1 resulted from 0.01‐0.25 mm–thick melanomas; however, the risk for death within 10 years was greater for those diagnosed with melanoma when tumor depth was 0.01‐0.25 mm than for those diagnosed when tumor depth was 0.26‐0.50 mm. Prognosis worsened with depths starting at 0.51 mm. The pattern within T1 was not explained by ulceration. Limitations: We did not evaluate melanoma subtype, mitotic rate, or other associated features. Conclusion: Thin melanomas are a substantial public health burden. Efforts should be made to diagnose melanoma at the in situ stage.