The process by which cutaneous melanoma greater than 2 mm thick must be excised is controversial. In a study with a mean follow-up of 5 years, researchers showed by results of a previously published randomized trial of narrow (1 cm) vs. wide (3 cm) thick excision margins in patients with cutaneous melanoma that narrow margins increased the frequency of local recurrence, but there was no significant difference in overall survival. The researchers report a long-term survival analysis of this trial. The researchers did a randomized, open multicenter trial in 59 hospitals, 57 in the United Kingdom, one in Poland and one in South Africa. Patients with primary localized cutaneous melanoma and melanoma breslov thickness greater than 2 mm on the upper trunk or extremities (excluding palms or feet) were randomly assigned (1:1) to undergo surgery (either for a 1 cm or 3 cm resection margin). Randomized lists were generated by randomizing replacement blocks and stratified by center and extent of initial surgery. The endpoints of this analysis were overall survival and melanoma-specific survival. The analysis was performed in the intention-to-treat population. Between December 16, 1992, and May 22, 2001, researchers randomly assigned 900 patients to undergo surgery with a 1-cm margin (n=453) or 3 (n=447). At a mean follow-up of 8.8 years (106 months [IQR 76-135]), 494 patients died, and 359 of these deaths were attributed to melanoma in the 1 cm group 194 deaths were attributed to melanoma and 165 in the 3 cm margin group (unadjusted risk ratio). Although the overall mortality rate was higher in the 1-cm margin group than in the 3-cm margin group (253 vs. 241), the difference was not significant unadjusted. 35 (8%) patients in the 1-cm group had surgical complications and 65 (15%) patients in the 3-cm group had surgical complications. The results of this study suggest that a 1-cm margin is not sufficient for patients with cutaneous melanoma with a Breslov thickness greater than 2 mm on the trunk and extremities. Current guidelines recommend receiving 2 cm margins for patients with greater than 2 mm thickness, but only 1 cm margins for thinner melanomas. The adequacy of 1-cm margins for thinner melanomas with poor prognosis should be addressed in future randomized studies.