The clinical efficacy and safety of a 2-cm resection margin for melanoma thicker than 2 mm is supported by study data published in the Lancet.  

Investigators conducted a randomized controlled trial at 53 hospitals across Sweden, Denmark, Estonia, and Norway. Eligible patients had cutaneous melanoma >2 mm with a primary site on the trunk or upper or lower extremities. Patients were randomly assigned to treatment with either a 2-cm or 4-cm excision margin, after which they were followed until death or conclusion of the study period. Information on date and cause of death was abstracted from medical records, local cancer registries, and national cause-of-death registries. Cox proportional hazards models were used to estimate hazard ratios (HRs) for overall survival and melanoma-specific survival across study groups.

Between January 22, 1992 and May 19, 2004, 936 patients were recruited and randomly assigned to treatment with a 4-cm (n=465) or 2-cm excision margin (n=471). Patients were followed-up for a median of 19.6 years (interquartile range, 16.7 to 21.7 years). A total of 621 patients died during follow-up; 317 (51%) in the 4-cm margin group and 304 (49%) in the 2-cm margin group (unadjusted HR, 0.98; 95% CI, 0.83-1.14; P =.75). Of deaths attributed to melanoma (n=397), 52% (n=205) occurred in the 4-cm excision margin group and 48% (n=192) in the 2-cm excision margin group (unadjusted HR, 0.95; 95% CI, 0.78-1.16; P =.61). The incidence of melanoma-related mortality and all-cause mortality did not differ between study groups. Per multivariate analysis, adjustment for prognostic factors did not change the HRs of survival in either excision margin group. The highest risk for melanoma-related death was observed in patients with the following combined factors: male gender, age >60 years, ulcerated melanoma of thickness >3mm, primary location on the trunk.

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As a study limitation, investigators noted that nodal staging had not been performed during the study period, possibly resulting in an imbalance in nodal stage between treatment arms. In addition, pathologic excision margins were not recorded, limiting data applicability to surgical margins only. Even so, “this study provides robust data that a 2-cm resection margin is safe for melanoma thicker than 2 mm,” investigators wrote.

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Utjés D, Malmstedt J, Teras J, et al. 2-cm versus 4-cm surgical excision margins for primary cutaneous melanoma thicker than 2 mm: long-term follow-up of a multicentre, randomised trial. Lancet. 2019;394(10197):471-477.