Mortality burden and prognosis of thin melanomas overall and by subcategory of thickness, SEER registry data, 1992-2013.

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.