Striking increase of thin melanomas contrasts with stable incidence of thick melanomas

Objective: The aim of this study was to analyze the temporal evolution of m elanoma incidence in the department of the Bas-Rhin, France, and to Study t he evolution of tumor thickness. Design: Retrospective study including all histologically proven melanomas r ecorded at the cancer registry of the department of the Bas-Rhin between Ja nuary 1980 and December 1992 and at the Cutaneous Histopathology Department of the University Hospitals, Strasbourg, between January 1980 and December 1997. Setting: Population-based cancer registry and academic cutaneous histopatho logy department. Patients: A total of 1254 patients with histologically proven melanomas. Intervention: None. Main Outcome Measures: Temporal evolution of melanoma incidence and tumor t hickness. Results: The mean (SD) and median tumor thicknesses were 1.48 (1.59) mm and 0.87 mm, respectively, and they decreased during the study period. The inc rease in the number of melanomas was mainly related to an increase of super ficial spreading melanomas in both sexes. The number of intermediate melano mas (1-2 mm) in both sexes and the number of melanomas with a Breslow index between 2 and 4 mm in women increased only slightly. The number of melanom as with a Breslow index greater than 2 mm in men and greater than 4 mm in w omen remained stable during the reference period. Conclusion: A striking increase in incidence of thin melanomas contrasts wi th a stable incidence of thick melanomas.