De Novo vs Nevus-Associated Melanomas: Differences in Associations With Prognostic Indicators and Survival

Abstract

Background: Although 20% to 30% of melanomas are histopathologically 'nevus associated,' the majority of melanomas arise de novo, ie, in clinically normal skin with no associated nevus. We examined whether these forms of melanoma differed in their associations with clinical and histopathologic features and patient survival. Methods: We analyzed two prospective cohorts from our institution with protocol-driven follow-up information (NYU1, n = 1024; NYU2, n = 1125). We used univariate and multivariable analyses to examine associations between de novo vs nevus-associated melanoma classification and age, anatomic site, tumor thickness, tumor ulceration, mitotic index, histological subtype, clinical stage, and survival. We tested the associations identified in NYU1 using NYU2 as a replication cohort. All tests of statistical significance were two-sided. Results: In NYU1, de novo melanomas were associated with tumor thickness greater than 1.0 mm (odds ratio [OR] = 1.96, 95% confidence interval [CI] = 1.43 to 2.70, P